Chapter 8
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Field Maintenance Guidelines For Mature Rubber Area
A. Control of Weeds, Plant Diseases and Other Plantation Hazards 1.
Guidelines for Weeds Control 1.1 Introduction Weeding must be continued throughout the mature rubber period in order to minimize vegetative competition with Hevea and cover crops. Improved tree vigor will result in greater yields. A sound weeding policy also facilitates tapper movements within tree rows contributing to productivity. Cleanliness will also help prevent conditions conducive to fungal diseases of both the panel and tree canopy. The objective of weeding is to obtain a ground condition in mature rubber of bare tree rows, with avenues populated by a mixture of leguminous covers and desirable species of natural vegetation.
EXHIBIT 5: A Well maintained newly tapped rubber
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1.2 Weeding in Mature Rubber a. The objective is to keep tree rows clean throughout the year. Management should allocate a minimum of 3 rounds of chemical spraying per year. The main season for weeding of mature rubber is just prior to fertilizer application. It is also beneficial to spray prior to the wintering period of rubber trees. Start weeding all the early wintering clones first and the late winterers later. b. In young areas, once trees have brown bark up to at least one meter from the ground and have no leaves lower than one meter, chemical spraying may be applied. Ring weeding may be started in these areas using appropriate commercial herbicides (eg. Round-up ( Glyphosate) applied at 0 .5 kgs to 0.75 kgs a.i. /hectare for cogon and other perennial grasses, and 2, 4-D Amine at 1.0 kgs a.i./hectare for broad leaf weeds like mikania weed species. c. Strip spraying should be started as soon as the crown starts to provide a certain amount of shade to help reduce weeds re-growth. Herbicides to be used would depend on the dominant weed species present in the area. d. The objective is to keep first the circles and then the tree rows clean at all times. Weeding should be repeated whenever there is 50% weeds re-growth. e. After strip spraying, the inter-rows must be kept clean with periodic rounds of brushing / slashing up to four rounds a year depending on the actual ground conditions. If the area is still clean, delay the weeding cycle. 1.3 General Rules to Observe when Weeding a. Weeding is the single biggest expense after tapping. Therefore weeding must be done correctly the first time. b. All weeding crews must have a trained supervisor and capataz incharge.
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c. Trained coop personnel must be assigned to maintain the equipment. d. The Field maintenance section must maintain, under close control, a stock of replacement parts for all types of sprayers being used. e. No leaky sprayers may be used. Waste chemicals may endanger the operator and environment. f. Sprayer nozzles should be changed twice a year so that their calibration remains accurate. g. All chemicals should be accurately measured into a drum using accurate measuring devices. All herbicide application must use sticker spreader, unless specific instructions to the contrary are given. Efficacy of the chemicals must be maximized. h. No half full drums with surplus chemicals should be poured away. This may leads to poisoning of the immediate environs. Allow overtime work if necessary to use up the chemical, but try to fix a task that will not result in unused chemical solutions at the end of the day. i.
Herbicides are poisonous. Workers must wash their hands in clean water prior to eating or smoking.
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2.
Root Disease 2.1 Introduction Root diseases are a group of highly destructive fungal pathogens of tropical woody crops, capable of directly killing rubber trees of all ages and causing increasing vacancies in the stand. Originating from naturally infected trees in the jungle, the diseases survived in the boles and roots when these trees were cut down, and spread to rubber by root contact. Strands or sheets of fungal mycelium called rhizomorphs grow across such contacts and spread along the roots, progressively penetrating and killing them. The disease advances through the lateral roots to the collar and tap roots, finally killing the tree. The dead tree then becomes source for a second phase of spread, to its neighbors as the trees grow and their root systems meet. New centers of infection can also arise through wind-borne or insectborne spores of the pathogens, colonizing tree stumps and surface timber left not cleared at the time of planting or replanting. Broken ends of branches and trunk resulting from wind damages and pruning or pollarding cuts also become substratum for spores to start an infection, which then spreads down to the roots. Symptoms of root diseases follow those arising from gradual cutting off of water and nutrient supply from the soil and could be visibly observed through the desiccation of bark surface, change of leaf color, defoliation, die-back and eventual death of the trees. Premature flowering and fruiting can also be seen in addition to the above symptoms. Below the ground, the diseased roots are very rough and encrusted with the invading fungus, in contrast to the flesh colored look and smooth surface of healthy roots.
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2.2 The Diseases Four species of fungi are responsible for root diseases of rubber. These, in their order of importance, are as follows:
Rigidoporus lignosus causes white root disease. Phellinus noxious causes brown root disease. Ganoderma pseudoferrum causes red root disease. Ustulina zonata causes collar and root rot.
White root disease is the most common of the four, usually making its appearance 6-12 months after planting and making it an important disease to watch for in immature rubber. Brown and red root diseases can also be found in young rubber, but they assume importance in mature rubber, because of their slower spread. Ustilina generally occurs in old or mature rubber. To identify the different root disease fungi in the field, two things are examined: rhizomorphs on the diseased roots and fruiting bodies on dead or dying trees. a. RIGIDOPORUS LIGNOSUS (White Root Disease) Rhizomorphs. Rhizomorphs are pale white branching strands ramifying into a network and firmly attached to affected roots. They become yellowish or light brown with age. The advancing end of the fungal strands is well ahead of the portion of the root penetrated and killed by the fungus (sometimes up to a meter or more). It should be remembered that white rhizomorphs are also produced by some species of harmless fungi, but they are loosely attached to the root surface and are not associated with death of any part of the root. Although direct infection of the collar and top root may occur, the fungi generally reach the collar by traveling inwards along the lateral roots from an infectious source nearby. CAP-PBD Post-Replanting Rubber Manual
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Often the rhizomorphs may be traced along one or more roots to a distance of several feet and may be seen to have had their origin in an old root stump nearby, or traced to a neighboring rubber tree. Gaps in the stand should lead to the suspicion that other trees in the vicinity may have been killed by root disease. The fruiting bodies are bracket-like, typically orange-yellow-colored on the upper surface and deep pink-orange on the lower surface. Spores. The spores are produced in the fruit bodies; when mature, they are disseminated by wind, rain and insects. If by chance the spores come to rest on a congenial host such as a rotting piece of wood, they may germinate and start a new source of infection. b. PHELLINUS NOXIOUS (Brown Root disease). Rhizomorphs: Unlike in white root disease, the rhizomorphs form a continuous skin over infected roots. The mycelium secretes a gum-liked fluid, to which earth and small stones adhere firmly and consequently the exterior of an infected root presents the appearance of a darkbrown rough encrustation. On scraping this encrustation, the typical brown color of the underlying mycelium may be seen. Washing makes the color easily visible. The fruiting bodies, are not as commonly met with as those of Rigidoporus lignosus. They are irregularly shaped brackets, deep brown in color, and generally pierced by grass stems or small twigs around which it has grown.
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c. GANODERMA PSEUDOFERRUM (Red Root Disease). As in brown root disease, the Rhizomorphs form a skin on the affected roots with adhering soil which however can be more easily washed with water to show the reddish brown color of the fungus. Rhizomorphs of white root disease that become reddish brown with age should not be mistaken for red root disease. A further distinguishing feature of this disease is that the rooted roots break into several layers when crushed. Fructifications are hard brackets in tiers, reddish-brown and wrinkled on the upper surface and gray-white below with a whitish fringe of the tap root. Trees infected at an advanced stage will invariably die. In older trees however, treatment has a chance of success if leaf symptoms appear only on one of two branches supplied by an infected lateral root. d. USTULINA ZONATA (Ustulina Trunk, Collar and Root Rot) Rhizomorphs are not produced on the surface of affected roots, but sheets of gray-white mycelium grow between the bark and surface of the wood. Affected area of the collar is often concealed by earth scrap, until fruit bodies develop as velvety gray plates pressed flat on the surface. As the plates enlarge they fuse with each other to become large dark-gray irregular patches with a zoned appearance.
2.3 Detection Of All Four (4) Diseases A regular and periodic tree by tree inspection of the field is essential for detecting trees affected by root diseases, in order that they can be given prompt treatment. Among the methods available the one that has proved harmless to the tree, fast and less expensive is looking for changes in the canopy color, because general discoloration of the foliage is the earliest symptom of any interruption of root function. CAP-PBD Post-Replanting Rubber Manual
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An experienced worker can detect very early the healthy foliage having turned to slightly off-green in certain part of the canopy, or on the whole tree if it is still young. The leaves attain a ripened appearance, in contrast to the deep green color on the unaffected branches, soon turning yellow and then brown and shriveled. Trees showing obvious foliage systems are often beyond saving by treatment, especially small trees, as infection would have already reached the collar or parts of the tap roots. These trees will invariably die. In older trees however, treatment has a chance of success if leaf symptoms appear only on one of two branches supplied by an infected lateral root. Therefore the merit of foliage inspection is not in saving every detected tree, but in pointing out a disease source and enabling prevention of neighboring trees becoming inflicted.
2.4 Treatment Procedures Trees marked as diseased during foliage inspection are generally those where the diseases is far too advanced to benefit from treatment, because there is no fungicide known that can kill and eradicate root disease fungi completely. However in older trees, if only a portion of the foliage in discolored, treatment has a chance of success. Treatment procedures therefore rely on preventing the loss of neighboring trees as well, because they would be the ones most likely to get the disease next, if not already infected. Protection is afforded by chemical application in the form of a dressing in bitumen base applied around the collar and base portions of the tap root and laterals after all diseased tissues are surgically removed and burnt, together with any disease sources found nearby. Commonly known as “Collar Protectant Dressing”, the one containing 20% quintozene (PCNB) is effective against white root disease. CAP-PBD Post-Replanting Rubber Manual
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It is sold under many trade names, such as Phytopaste, Ingropaste, Fomac-2, Fomotex, Shell Collar Protectant etc. For treatment of brown and red root diseases Calixin Collar Protectant containing 10% Tridemorph should be used, as quintozene is not effective.
2.5 Control in Mature Rubber A sound policy of root disease control lies in eliminating all disease from the field before the trees come to maturity, because it is much more expensive and laborious to treat in mature rubber. However, if treatment has been neglected or improperly applied during immaturity, considerable disease incidence can be expected to continue into the early mature period. The high economic potential of the trees at this stage makes it imperative that potential tree losses should be halted as quickly as possible. Mature rubber blocks are therefore divided into two categories for the purpose of root disease treatment: Young mature blocks less than 10 - 12 years old and being tapped on panel “A”, where the higher cost of treatment is justified and, older blocks excluding those scheduled for replanting in the next 5 or 6 years and those with poor yields and low stand, where only limited eradication and isolation of the disease is feasible.
2.6 Procedure for Detection and Treatment of Root Disease in Young Trees 2.6.1 Foliage Inspection Commence routine foliage inspection in immature rubber six months after planting. If disease incidence is not high (less than 12 cases per block) per inspection, then one inspection round every two months is adequate, but in fields of high and increasing incidence of root disease, inspection rounds should be done monthly up to 12 months from planting. CAP-PBD Post-Replanting Rubber Manual
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From the second year (13th month) foliage inspection must be done monthly, for as long as disease incidence is significant (12 cases or more per block per inspection round). At four years change to quarterly inspection if less than 5 cases per block were observed per inspection. Otherwise, continue monthly until incidence is lowered to 5 or less cases. Foliage inspection should be done by regular maintenance crews trained for the purpose. An experienced worker can detect the ripened appearance and slightly off-green color of the foliage of infected trees either entirely or on a part of the canopy, sometimes together with outof-season flowering or fruiting. Walking with his back to the sun along every fifth row or third row or every inter row, depending upon age of the field, he marks diseased trees with a plastic ribbon tied to the trunk, for the treatment gang to take further action. The worker must observe only fully mature leaves or foliage for leaf symptoms and avoid confusion with young leaves or symptoms of any old odium infection. 2.6.2 Collar and Lateral Root Inspection Collar inspection is done after a skilled detector gang has found disease symptoms, either from ripening-yellow leaves, heavy out of season flowering, or even rough bark. If there is any disease on the collar, all the neighboring trees shall also be checked and treated because it is possible that these trees are also infected. Infected trees detected by foliage symptoms during the first year of planting are generally too late for saving by treatment; therefore they are dug out and replaced with supplies. During the third and subsequent years, when supplying is not possible every effort must be made to save the trees.
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Only trees with more than 60% of circumference of the bole affected may be pulled out in mature blocks; while in young mature blocks, trees even with 80% of the bole affected have a chance of survival by treatment if there are at least two lateral roots still healthy. All the trees marked with plastic ribbons at the time of foliage inspection should be collar inspected. a. Carefully dig out the soil from around the collar of the tree marked as diseased with a flat-pointed wooden stick to expose the base of lateral roots until the upper portion of the tap root becomes visible all round. This is called collar inspection. Infected trees are identified through the following: (1) If Rhizomorphs are firmly attached, they may have penetrated into the affected roots and killed some of the roots. (2)
If the leaves have attained a ripened appearance, in contrast to the deep green color of healthy branches. When excavated, the rhizomorphs are still loosely attached to the roots surface.
(3) If fruiting bodies have already grown and developed on the ground surface near or even attached to the tree. b. Determine the identity of pathogen whether white, brown or red root disease. c. If a major portion of the collar and tap root is penetrated and killed by the fungus, mark the tree with a cross of black paint, for eradication by digging out and burning. If only small portions are affected or if the necrosis is only superficial, mark it for treatment, so it can be saved along with its neighbors. 2.6.3 Inspection of Neighboring Trees Carry out collar inspection of the two immediate neighboring trees in the row. If one or both are already found infected, collar inspect the
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trees next to them, continuing in both directions until a healthy tree is reached. In a field of quincunx planting (4.5m x 4.5m), collar inspect all the six surrounding trees. When planting is 6m x 3.25 meters, inspect the 2 trees (left and right) next to the infected trees on the line only. Subject all collar inspected trees to treatment and call them uninfected controls. 2.6.4 Exposure of Base of Tap Root and Laterals Continue removing the soil from around the tree until a bowl-like cavity 15 - 30 cm radius and 10 - 30 cm deep is created around the tree, the size of the bowl depending upon the size of the tree. The opening should be deep enough to extend to just below the lowest lateral root and just sufficient to give access to all diseased portions of the tap root and base of the laterals. Care should be taken to avoid injuring the roots as far as possible. 2.6.5 Tracing and Cutting Diseased Lateral Among the laterals standing exposed in the cavity, locate any that are entirely or partially dead and covered with mycelium of one of the pathogens. Since these laterals probably bring the infection from some source nearby, trace the lateral out until the source of infection is found. In the tree rows on contour lines, inspection of affected roots from neighboring trees is to be confined only on the same row of infected trees. Where the infection is found to originate directly from the collar, the fungal mycellium and the death of underlying tissues generally surround the entire collar and then spread outwards along the lateral roots and downwards along the tap root.
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Similarly, in cases where the infection originates from deep down in the tap root, it spreads upwards and surrounds the collar, and then outwards along the lateral roots. These situations are in contrast to infection coming inwards to the collar from an outside source along one of the laterals. Check with a blunt metal or bamboo scraper the extent of the lateral root that is dead, and cut away only its dead portion with a sharp knife or chisel. Keep the cut away laterals separately for burning, together with any infection source located in the planting row. 2.6.6 Surgical Removal of Diseased Tissues. If the disease has already progressed to the collar and has penetrated some part of it or the tap root, the full extent of the dead areas should be checked with the blunt scraper without injuring the healthy bark. Before checking, clean away all soil from the exposed roots with a piece of cloth. Using appropriate implements, which may include scrapers, knives, a small saw, chisels of different sizes, mallet, etc., carefully remove all diseased portions of the bark and wood. The implements should be kept sharpened for each day's use. This surgical process is completed only when no trace of any necrotic or discolored tissue is left behind. All bark and wood pieces thus removed are to be kept separately for burning later. 2.6.7 Application of Collar Protectant Dressing The exposed collar, base of laterals and upper portion of the tap root are wiped clean with a cloth to remove any adhering soil.
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The appropriate collar protectant dressing is then applied on them with a brush, ensuring that the collar and tap root are covered all round including the entire area that had been subjected to surgery, including the severed ends of lateral roots. The base of laterals are covered to a distance of 10 - 20 cm, depending upon tree size, using a small hand mirror to check any uncovered areas underneath. Small feeder roots may be cut away before applying the dressing. All opened trees must be treated with PCNB collar protectant even where no disease is found. NOTES: Use only Calixin Collar Protectant dressing for brown and red root disease. The cheaper PCNB formulation such as Phytopaste, Ingropaste, Fomac-2, Fomotex, Shell Collar Protectant etc., are effective only for white root disease. At the end of the day's work the cavity around the tree should be refilled with soil. The same soil that was removed earlier can be used provided care is taken to see that pieces of wood and bark removed during treatment have not been mixed in it. It is preferable to wait for a couple of hours after applying the collar protectant before refilling the hole, to allow drying of the treated surface. Pile the earth up around the tree to prevent water logging. For young trees “ties” may be used to keep the trees upright. Pollard or prune the trees where necessary. The trained capataz is responsible to see the following work is done: 1. 2. 3. 4.
excision of dead tissue. application of collar protectant. removal and burning of all dead woody material. mark the trees as treated before the hole is refilled.
2.6.8
Disposal of Infected Debris
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All dead and diseased roots and pieces of bark and wood resulting from surgery must be separated from excavated soil. These must be collected together with any infection source located during treatment. Burn all debris properly. 2.6.9
Marking of Treatment Trees
Mark all treated trees with a solid black ring of paint on the trunk, at 1.5 to 1.7 meter from the ground. Diseased trees that are treated get a complete ring, while their healthy neighbors treated after collar inspection are given a broken ring of the same color. Write the month and year of treatment just above the ring, and the initials of the disease, example: RL ( Rigidoporus lignosus), GP ( Ganoderma pseudoferium) and etc. 2.6.10
Re-inspection and Treatment
Treatment using collar protectant should be able to protect the root from further disease attack for about two years. Therefore, treated trees must be re-opened after two years to remove any fresh infection coming from outside the treated zone, and applied collar dressing before putting back the soil. In the case of immature rubber where roots are growing very actively, re-inspection and re-treatment should be carried out as follows:
Up to the age of 3 years, the second inspection it is advisable to do 12 months after the first inspection.
At the age of more than 3 years, under normal conditions, retreatment should be done 24 months after the first treatment.
2.6.11
Marks on Re-inspected and Re-treated Trees
If the trees are still infected, mark them with a continuous ring with dates (only month and year)
If they have recovered, and are disease free, mark them with a disconnected ring complete with date.
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The neighboring trees which were formerly marked with disconnected rings and are now obviously infected, are to be treated and remarked according to the disease found. 2.6.12 Root Disease Records
It is important to keep a complete record of disease incidence and treatment for each block, with the following information enumerated after each round of inspection and treatment: a. trees showing foliage symptoms. b. Trees collar inspected (include 6 neighbors) c. trees confirmed infected. d. trees removed as dying or beyond treatment. e. previously treated trees subsequently removed as dying or dead. f. newly uninfected trees treated (with incomplete ring) 1. PCNB
2. CALIXIN
g. previously treated trees retreated 1. PCNB
2. CALIXIN
h) uninfected trees treated 1. PCNB
2. CALIXIN
Monitor the progress of disease and success of treatment measures from these records at yearly intervals.
2.7 Treatment Procedures for Root Disease Control in Young Mature Rubber - Panel (BO-1). Treatment procedures during early years of maturity when the trees are still tapped on Panel A (BO-1) are more or less the same for immature rubber, but with adjustments made for the larger size of the trees. The following procedures must be observed : 2.7.1
Foliage Inspection
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Institute row-by-row foliage inspection every 1 to 3 months, depending upon the extent of incidence, to detect and mark diseased trees. Because of wintering, inspection should not be conducted from March-May but before and after this period. Trees that have the entire canopy affected are marked separately with a black “X” mark for subsequent removal together with their entire root system, as they cannot be saved. Their neighbors on either side should be treated. Signs of out of season flowers or fruiting should be looked for. These frequently signify presence of root disease. On one hand, trees exhibiting foliage symptoms on one or two branches on one side generally have a major lateral on the opposite side that is diseased. They can be protected by treatment. 2.7.2
Collar and Lateral Root Inspection
For trees exhibiting diseased symptoms, inspection must be done from the collar down to the level of the lowest lateral root to confirm the disease and assess its severity and extent. If the disease has progressed to affect more than 90% of the collar and top of the root, further effort to save that tree is not worthwhile: The trees should then be marked for removal with a black “X” mark. Collar inspection is then continued on neighboring trees on either side of the row until a healthy tree is reached. 2.7.3
Exposure of Base of Tap Root and Laterals
The soil around the bole to a radius of 35 - 45 cms should be opened to expose the base of laterals and top of tap root of the trees marked for treatment, infected as well as the healthy trees immediately next to them. 2.7.4 Inspection to Demarcated Diseased Parts
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Inspect the exposed root system to assess the extent of diseased portions, by scraping small slices of superficial bark with a blunt scraper. 2.7.5 Tracing and Cutting Diseased Laterals Trace any diseased lateral to its source. This should be continued even into the inter-rows as the roots are large and legume covers already thin. In the tree rows on contour lines, inspection of affected roots from neighboring trees is to be confined only on the same row of infected trees. Cut off the diseased portion of the lateral and remove the infection source entirely, and burn it. 2.7.6 Surgical Removal of Diseased Tissues If the disease has already reached the collar, surgically remove every trace of necrotic tissue from it and from the top portion of tap root and base of laterals down to healthy wood. If the disease has progressed deeper down along the tap root, treatment may be abandoned and the tree removed (dug out and burned). In case where a large amount of root is cut away topping may be indicated or branch pruning may be necessary. Use of “ties” to keep tree upright may also be necessary. 2.7.7 Application of Collar Protectant Dressing Wipe the exposed root system clean of soil particles with a piece of cloth; do not scrape healthy roots. Next, apply the appropriate collar protectant dressing all around the collar and top 10 cm or more of the tap root to cover all areas which have undergone surgery. Apply the dressing also to the base of laterals all round up to a distance of 20-25 cm and to the cut ends of any severed laterals. Small feeder roots may be cut away before applying the dressing. CAP-PBD Post-Replanting Rubber Manual
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2.7.8 Refilling Hole Refill the hole with the same soil making sure there is no fragments of root or other diseased materials mixed in it. Pile earth up around tree base to prevent water logging, and enough to permit rain water to run off and not pool. 2.7.9 Disposal of Infected Debris Collect and burn all diseased materials, such as roots, root-fragments, pieces of bark and wood, disease sources and root system of trees removed. Marking Treated Trees Mark all treated trees with a solid black paint ring in the trunk at 1.70 meters from the ground. Mark the initials of the disease above the ring as follows: R.L = Rigidoporus Lignosus. P.N = Phellinus Noxious. G.P = Ganoderma Pseudoferrum. U.Z = Ustulina Zonata. Diseased trees that are treated get a solid line complete ring, while their healthy neighbors which were inspected and treated are given a broken- line incomplete ring at the same height. Paint the month and year of treatment just above the ring. 2.7.10 Re- Treatment Open back the soil around collar of all treated trees after two years for any new infection and retreat them, unless new symptoms appear before two years, in which case the tree must be retreated promptly
2.8 Treatment Procedures for Root Disease Control in Mature Rubber.
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Control of root disease in mature rubber older than those being tapped on Panel A (BO-1) is difficult and prohibitively expensive. Nevertheless, some limited treatment can be justified in high yielding blocks that have a good stand. The procedures adopted for reducing tree losses comprise localized eradication of diseased material and isolation of affected areas of the field by digging isolation trenches. 2.8.1 Tree Inspection A row-by-row inspection is made every six months, to identify dead trees and marking them. 2.8.2 Disposal of Dead and Dying Trees Remove all dead and dying trees with their entire root system as well as any sources of infection traced through them. All infected root materials should then be collected and burned. 2.8.3 Collar and Lateral Root Inspection Inspect the collar and lateral root bases of the two trees on either side of the eradicated tree in the same row. If any of them is found infected, the tree next to it is collar inspected until a healthy tree is found. The soil around the tree should be dug out until the base of laterals are exposed for inspection. 2.8.4
Digging Isolation Trench
A simple isolation trench is dug midway between the last diseased tree and its immediate healthy neighbor at both ends, cutting across the planting row. If any infected roots are discovered in this trench, it is abandoned and a fresh one dug that includes that healthy tree as well. Isolation trenches are dug 30 cm wide and 60 cm deep. CAP-PBD Post-Replanting Rubber Manual
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2.8.5 Extension of Isolation Trench Extend the simple trench, to half the width of the inter-row on either side. Infected trees coming within the trench are tapped until they start dying, after which they are removed and burned. 2.8.6 Completion of Isolation Trench If many trees in a row or more than one adjacent row are affected, the trenches across the rows are connected to enclose the entire effected area by digging a trench lengthwise along the middle of the inter row on either side. Figure (b) below. (a)
(b)
X
X
X
X
X
X
X
X
X X
2.8.7 Disease Patches Small disease patches if any, are also enclosed in an isolation trench around the patch, constructed as in figure (a) above. However, this may become prohibitively costly for medium and large patches, a decision should be made based on calculated benefits and costs on whether to proceed or not. 2.8.8 Maintenance of Isolation Trench Isolation trenches should be inspected every twelve months to dig out any soil that may have eroded in, so that the correct width and depth are maintained, and any roots going through are severed and removed.
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2.8.9 Treatment of Wind Damage Promptly attend to trunk snap and branch breakages resulting from wind damage, to avoid spore infection of cut ends especially by brown root disease. Prune them to a slanting clean surface and apply a wound dressing containing coaltar fungicide such as 20% Izal in bitumen emulsion. 2.8.10 Treatment of USTULINA For treatment of Ustulina trunk collar and root rot, cut away all diseased tissues from the base of the trunk, collar and affected portion of the roots until only healthy tissues are exposed, and cover the wound with the above dressing. The hollow of the collar resulting from the extensive surgery may sometimes need reinforcement with cement for the tree to stand strong winds. 2.7.11 Root Disease Records It is important to keep a complete record of disease incidence and treatment for each block, with the following information enumerated after each round of inspection and treatment: a) Dates and locations of infection and treatment. b) Number of trees collar inspected. c) Trees confirmed infected after collar inspection. (invariably to be removed sooner or later). d) Number of trees showing foliage symptoms. (invariably to be removed)
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A. Control of Weeds, Plant Diseases and Other Plantation Hazards 1.
Guidelines for Weeds Control 1.1 Introduction Weeding must be continued throughout the mature rubber period in order to minimize vegetative competition with Hevea and cover crops. Improved tree vigor will result in greater yields. A sound weeding policy also facilitates tapper movements within tree rows contributing to productivity. Cleanliness will also help prevent conditions conducive to fungal diseases of both the panel and tree canopy. The objective of weeding is to obtain a ground condition in mature rubber of bare tree rows, with avenues populated by a mixture of leguminous covers and desirable species of natural vegetation.
EXHIBIT 5: A Well maintained newly tapped rubber
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1.2 Weeding in Mature Rubber a. The objective is to keep tree rows clean throughout the year. Management should allocate a minimum of 3 rounds of chemical spraying per year. The main season for weeding of mature rubber is just prior to fertilizer application. It is also beneficial to spray prior to the wintering period of rubber trees. Start weeding all the early wintering clones first and the late winterers later. b. In young areas, once trees have brown bark up to at least one meter from the ground and have no leaves lower than one meter, chemical spraying may be applied. Ring weeding may be started in these areas using appropriate commercial herbicides (eg. Round-up ( Glyphosate) applied at 0 .5 kgs to 0.75 kgs a.i. /hectare for cogon and other perennial grasses, and 2, 4-D Amine at 1.0 kgs a.i./hectare for broad leaf weeds like mikania weed species. c. Strip spraying should be started as soon as the crown starts to provide a certain amount of shade to help reduce weeds re-growth. Herbicides to be used would depend on the dominant weed species present in the area. d. The objective is to keep first the circles and then the tree rows clean at all times. Weeding should be repeated whenever there is 50% weeds re-growth. e. After strip spraying, the inter-rows must be kept clean with periodic rounds of brushing / slashing up to four rounds a year depending on the actual ground conditions. If the area is still clean, delay the weeding cycle. 1.3 General Rules to Observe when Weeding a. Weeding is the single biggest expense after tapping. Therefore weeding must be done correctly the first time. b. All weeding crews must have a trained supervisor and capataz incharge.
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c. Trained coop personnel must be assigned to maintain the equipment. d. The Field maintenance section must maintain, under close control, a stock of replacement parts for all types of sprayers being used. e. No leaky sprayers may be used. Waste chemicals may endanger the operator and environment. f. Sprayer nozzles should be changed twice a year so that their calibration remains accurate. g. All chemicals should be accurately measured into a drum using accurate measuring devices. All herbicide application must use sticker spreader, unless specific instructions to the contrary are given. Efficacy of the chemicals must be maximized. h. No half full drums with surplus chemicals should be poured away. This may leads to poisoning of the immediate environs. Allow overtime work if necessary to use up the chemical, but try to fix a task that will not result in unused chemical solutions at the end of the day. i.
Herbicides are poisonous. Workers must wash their hands in clean water prior to eating or smoking.
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2.
Root Disease 2.1 Introduction Root diseases are a group of highly destructive fungal pathogens of tropical woody crops, capable of directly killing rubber trees of all ages and causing increasing vacancies in the stand. Originating from naturally infected trees in the jungle, the diseases survived in the boles and roots when these trees were cut down, and spread to rubber by root contact. Strands or sheets of fungal mycelium called rhizomorphs grow across such contacts and spread along the roots, progressively penetrating and killing them. The disease advances through the lateral roots to the collar and tap roots, finally killing the tree. The dead tree then becomes source for a second phase of spread, to its neighbors as the trees grow and their root systems meet. New centers of infection can also arise through wind-borne or insectborne spores of the pathogens, colonizing tree stumps and surface timber left not cleared at the time of planting or replanting. Broken ends of branches and trunk resulting from wind damages and pruning or pollarding cuts also become substratum for spores to start an infection, which then spreads down to the roots. Symptoms of root diseases follow those arising from gradual cutting off of water and nutrient supply from the soil and could be visibly observed through the desiccation of bark surface, change of leaf color, defoliation, die-back and eventual death of the trees. Premature flowering and fruiting can also be seen in addition to the above symptoms. Below the ground, the diseased roots are very rough and encrusted with the invading fungus, in contrast to the flesh colored look and smooth surface of healthy roots.
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2.2 The Diseases Four species of fungi are responsible for root diseases of rubber. These, in their order of importance, are as follows:
Rigidoporus lignosus causes white root disease. Phellinus noxious causes brown root disease. Ganoderma pseudoferrum causes red root disease. Ustulina zonata causes collar and root rot.
White root disease is the most common of the four, usually making its appearance 6-12 months after planting and making it an important disease to watch for in immature rubber. Brown and red root diseases can also be found in young rubber, but they assume importance in mature rubber, because of their slower spread. Ustilina generally occurs in old or mature rubber. To identify the different root disease fungi in the field, two things are examined: rhizomorphs on the diseased roots and fruiting bodies on dead or dying trees. a. RIGIDOPORUS LIGNOSUS (White Root Disease) Rhizomorphs. Rhizomorphs are pale white branching strands ramifying into a network and firmly attached to affected roots. They become yellowish or light brown with age. The advancing end of the fungal strands is well ahead of the portion of the root penetrated and killed by the fungus (sometimes up to a meter or more). It should be remembered that white rhizomorphs are also produced by some species of harmless fungi, but they are loosely attached to the root surface and are not associated with death of any part of the root. Although direct infection of the collar and top root may occur, the fungi generally reach the collar by traveling inwards along the lateral roots from an infectious source nearby. CAP-PBD Post-Replanting Rubber Manual
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Often the rhizomorphs may be traced along one or more roots to a distance of several feet and may be seen to have had their origin in an old root stump nearby, or traced to a neighboring rubber tree. Gaps in the stand should lead to the suspicion that other trees in the vicinity may have been killed by root disease. The fruiting bodies are bracket-like, typically orange-yellow-colored on the upper surface and deep pink-orange on the lower surface. Spores. The spores are produced in the fruit bodies; when mature, they are disseminated by wind, rain and insects. If by chance the spores come to rest on a congenial host such as a rotting piece of wood, they may germinate and start a new source of infection. b. PHELLINUS NOXIOUS (Brown Root disease). Rhizomorphs: Unlike in white root disease, the rhizomorphs form a continuous skin over infected roots. The mycelium secretes a gum-liked fluid, to which earth and small stones adhere firmly and consequently the exterior of an infected root presents the appearance of a darkbrown rough encrustation. On scraping this encrustation, the typical brown color of the underlying mycelium may be seen. Washing makes the color easily visible. The fruiting bodies, are not as commonly met with as those of Rigidoporus lignosus. They are irregularly shaped brackets, deep brown in color, and generally pierced by grass stems or small twigs around which it has grown.
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c. GANODERMA PSEUDOFERRUM (Red Root Disease). As in brown root disease, the Rhizomorphs form a skin on the affected roots with adhering soil which however can be more easily washed with water to show the reddish brown color of the fungus. Rhizomorphs of white root disease that become reddish brown with age should not be mistaken for red root disease. A further distinguishing feature of this disease is that the rooted roots break into several layers when crushed. Fructifications are hard brackets in tiers, reddish-brown and wrinkled on the upper surface and gray-white below with a whitish fringe of the tap root. Trees infected at an advanced stage will invariably die. In older trees however, treatment has a chance of success if leaf symptoms appear only on one of two branches supplied by an infected lateral root. d. USTULINA ZONATA (Ustulina Trunk, Collar and Root Rot) Rhizomorphs are not produced on the surface of affected roots, but sheets of gray-white mycelium grow between the bark and surface of the wood. Affected area of the collar is often concealed by earth scrap, until fruit bodies develop as velvety gray plates pressed flat on the surface. As the plates enlarge they fuse with each other to become large dark-gray irregular patches with a zoned appearance.
2.3 Detection Of All Four (4) Diseases A regular and periodic tree by tree inspection of the field is essential for detecting trees affected by root diseases, in order that they can be given prompt treatment. Among the methods available the one that has proved harmless to the tree, fast and less expensive is looking for changes in the canopy color, because general discoloration of the foliage is the earliest symptom of any interruption of root function. CAP-PBD Post-Replanting Rubber Manual
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An experienced worker can detect very early the healthy foliage having turned to slightly off-green in certain part of the canopy, or on the whole tree if it is still young. The leaves attain a ripened appearance, in contrast to the deep green color on the unaffected branches, soon turning yellow and then brown and shriveled. Trees showing obvious foliage systems are often beyond saving by treatment, especially small trees, as infection would have already reached the collar or parts of the tap roots. These trees will invariably die. In older trees however, treatment has a chance of success if leaf symptoms appear only on one of two branches supplied by an infected lateral root. Therefore the merit of foliage inspection is not in saving every detected tree, but in pointing out a disease source and enabling prevention of neighboring trees becoming inflicted.
2.4 Treatment Procedures Trees marked as diseased during foliage inspection are generally those where the diseases is far too advanced to benefit from treatment, because there is no fungicide known that can kill and eradicate root disease fungi completely. However in older trees, if only a portion of the foliage in discolored, treatment has a chance of success. Treatment procedures therefore rely on preventing the loss of neighboring trees as well, because they would be the ones most likely to get the disease next, if not already infected. Protection is afforded by chemical application in the form of a dressing in bitumen base applied around the collar and base portions of the tap root and laterals after all diseased tissues are surgically removed and burnt, together with any disease sources found nearby. Commonly known as “Collar Protectant Dressing”, the one containing 20% quintozene (PCNB) is effective against white root disease. CAP-PBD Post-Replanting Rubber Manual
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It is sold under many trade names, such as Phytopaste, Ingropaste, Fomac-2, Fomotex, Shell Collar Protectant etc. For treatment of brown and red root diseases Calixin Collar Protectant containing 10% Tridemorph should be used, as quintozene is not effective.
2.5 Control in Mature Rubber A sound policy of root disease control lies in eliminating all disease from the field before the trees come to maturity, because it is much more expensive and laborious to treat in mature rubber. However, if treatment has been neglected or improperly applied during immaturity, considerable disease incidence can be expected to continue into the early mature period. The high economic potential of the trees at this stage makes it imperative that potential tree losses should be halted as quickly as possible. Mature rubber blocks are therefore divided into two categories for the purpose of root disease treatment: Young mature blocks less than 10 - 12 years old and being tapped on panel “A”, where the higher cost of treatment is justified and, older blocks excluding those scheduled for replanting in the next 5 or 6 years and those with poor yields and low stand, where only limited eradication and isolation of the disease is feasible.
2.6 Procedure for Detection and Treatment of Root Disease in Young Trees 2.6.1 Foliage Inspection Commence routine foliage inspection in immature rubber six months after planting. If disease incidence is not high (less than 12 cases per block) per inspection, then one inspection round every two months is adequate, but in fields of high and increasing incidence of root disease, inspection rounds should be done monthly up to 12 months from planting. CAP-PBD Post-Replanting Rubber Manual
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From the second year (13th month) foliage inspection must be done monthly, for as long as disease incidence is significant (12 cases or more per block per inspection round). At four years change to quarterly inspection if less than 5 cases per block were observed per inspection. Otherwise, continue monthly until incidence is lowered to 5 or less cases. Foliage inspection should be done by regular maintenance crews trained for the purpose. An experienced worker can detect the ripened appearance and slightly off-green color of the foliage of infected trees either entirely or on a part of the canopy, sometimes together with outof-season flowering or fruiting. Walking with his back to the sun along every fifth row or third row or every inter row, depending upon age of the field, he marks diseased trees with a plastic ribbon tied to the trunk, for the treatment gang to take further action. The worker must observe only fully mature leaves or foliage for leaf symptoms and avoid confusion with young leaves or symptoms of any old odium infection. 2.6.2 Collar and Lateral Root Inspection Collar inspection is done after a skilled detector gang has found disease symptoms, either from ripening-yellow leaves, heavy out of season flowering, or even rough bark. If there is any disease on the collar, all the neighboring trees shall also be checked and treated because it is possible that these trees are also infected. Infected trees detected by foliage symptoms during the first year of planting are generally too late for saving by treatment; therefore they are dug out and replaced with supplies. During the third and subsequent years, when supplying is not possible every effort must be made to save the trees.
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Only trees with more than 60% of circumference of the bole affected may be pulled out in mature blocks; while in young mature blocks, trees even with 80% of the bole affected have a chance of survival by treatment if there are at least two lateral roots still healthy. All the trees marked with plastic ribbons at the time of foliage inspection should be collar inspected. a. Carefully dig out the soil from around the collar of the tree marked as diseased with a flat-pointed wooden stick to expose the base of lateral roots until the upper portion of the tap root becomes visible all round. This is called collar inspection. Infected trees are identified through the following: (1) If Rhizomorphs are firmly attached, they may have penetrated into the affected roots and killed some of the roots. (2)
If the leaves have attained a ripened appearance, in contrast to the deep green color of healthy branches. When excavated, the rhizomorphs are still loosely attached to the roots surface.
(3) If fruiting bodies have already grown and developed on the ground surface near or even attached to the tree. b. Determine the identity of pathogen whether white, brown or red root disease. c. If a major portion of the collar and tap root is penetrated and killed by the fungus, mark the tree with a cross of black paint, for eradication by digging out and burning. If only small portions are affected or if the necrosis is only superficial, mark it for treatment, so it can be saved along with its neighbors. 2.6.3 Inspection of Neighboring Trees Carry out collar inspection of the two immediate neighboring trees in the row. If one or both are already found infected, collar inspect the
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trees next to them, continuing in both directions until a healthy tree is reached. In a field of quincunx planting (4.5m x 4.5m), collar inspect all the six surrounding trees. When planting is 6m x 3.25 meters, inspect the 2 trees (left and right) next to the infected trees on the line only. Subject all collar inspected trees to treatment and call them uninfected controls. 2.6.4 Exposure of Base of Tap Root and Laterals Continue removing the soil from around the tree until a bowl-like cavity 15 - 30 cm radius and 10 - 30 cm deep is created around the tree, the size of the bowl depending upon the size of the tree. The opening should be deep enough to extend to just below the lowest lateral root and just sufficient to give access to all diseased portions of the tap root and base of the laterals. Care should be taken to avoid injuring the roots as far as possible. 2.6.5 Tracing and Cutting Diseased Lateral Among the laterals standing exposed in the cavity, locate any that are entirely or partially dead and covered with mycelium of one of the pathogens. Since these laterals probably bring the infection from some source nearby, trace the lateral out until the source of infection is found. In the tree rows on contour lines, inspection of affected roots from neighboring trees is to be confined only on the same row of infected trees. Where the infection is found to originate directly from the collar, the fungal mycellium and the death of underlying tissues generally surround the entire collar and then spread outwards along the lateral roots and downwards along the tap root.
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Similarly, in cases where the infection originates from deep down in the tap root, it spreads upwards and surrounds the collar, and then outwards along the lateral roots. These situations are in contrast to infection coming inwards to the collar from an outside source along one of the laterals. Check with a blunt metal or bamboo scraper the extent of the lateral root that is dead, and cut away only its dead portion with a sharp knife or chisel. Keep the cut away laterals separately for burning, together with any infection source located in the planting row. 2.6.6 Surgical Removal of Diseased Tissues. If the disease has already progressed to the collar and has penetrated some part of it or the tap root, the full extent of the dead areas should be checked with the blunt scraper without injuring the healthy bark. Before checking, clean away all soil from the exposed roots with a piece of cloth. Using appropriate implements, which may include scrapers, knives, a small saw, chisels of different sizes, mallet, etc., carefully remove all diseased portions of the bark and wood. The implements should be kept sharpened for each day's use. This surgical process is completed only when no trace of any necrotic or discolored tissue is left behind. All bark and wood pieces thus removed are to be kept separately for burning later. 2.6.7 Application of Collar Protectant Dressing The exposed collar, base of laterals and upper portion of the tap root are wiped clean with a cloth to remove any adhering soil.
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The appropriate collar protectant dressing is then applied on them with a brush, ensuring that the collar and tap root are covered all round including the entire area that had been subjected to surgery, including the severed ends of lateral roots. The base of laterals are covered to a distance of 10 - 20 cm, depending upon tree size, using a small hand mirror to check any uncovered areas underneath. Small feeder roots may be cut away before applying the dressing. All opened trees must be treated with PCNB collar protectant even where no disease is found. NOTES: Use only Calixin Collar Protectant dressing for brown and red root disease. The cheaper PCNB formulation such as Phytopaste, Ingropaste, Fomac-2, Fomotex, Shell Collar Protectant etc., are effective only for white root disease. At the end of the day's work the cavity around the tree should be refilled with soil. The same soil that was removed earlier can be used provided care is taken to see that pieces of wood and bark removed during treatment have not been mixed in it. It is preferable to wait for a couple of hours after applying the collar protectant before refilling the hole, to allow drying of the treated surface. Pile the earth up around the tree to prevent water logging. For young trees “ties” may be used to keep the trees upright. Pollard or prune the trees where necessary. The trained capataz is responsible to see the following work is done: 1. 2. 3. 4.
excision of dead tissue. application of collar protectant. removal and burning of all dead woody material. mark the trees as treated before the hole is refilled.
2.6.8
Disposal of Infected Debris
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All dead and diseased roots and pieces of bark and wood resulting from surgery must be separated from excavated soil. These must be collected together with any infection source located during treatment. Burn all debris properly. 2.6.9
Marking of Treatment Trees
Mark all treated trees with a solid black ring of paint on the trunk, at 1.5 to 1.7 meter from the ground. Diseased trees that are treated get a complete ring, while their healthy neighbors treated after collar inspection are given a broken ring of the same color. Write the month and year of treatment just above the ring, and the initials of the disease, example: RL ( Rigidoporus lignosus), GP ( Ganoderma pseudoferium) and etc. 2.6.10
Re-inspection and Treatment
Treatment using collar protectant should be able to protect the root from further disease attack for about two years. Therefore, treated trees must be re-opened after two years to remove any fresh infection coming from outside the treated zone, and applied collar dressing before putting back the soil. In the case of immature rubber where roots are growing very actively, re-inspection and re-treatment should be carried out as follows:
Up to the age of 3 years, the second inspection it is advisable to do 12 months after the first inspection.
At the age of more than 3 years, under normal conditions, retreatment should be done 24 months after the first treatment.
2.6.11
Marks on Re-inspected and Re-treated Trees
If the trees are still infected, mark them with a continuous ring with dates (only month and year)
If they have recovered, and are disease free, mark them with a disconnected ring complete with date.
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The neighboring trees which were formerly marked with disconnected rings and are now obviously infected, are to be treated and remarked according to the disease found. 2.6.12 Root Disease Records
It is important to keep a complete record of disease incidence and treatment for each block, with the following information enumerated after each round of inspection and treatment: a. trees showing foliage symptoms. b. Trees collar inspected (include 6 neighbors) c. trees confirmed infected. d. trees removed as dying or beyond treatment. e. previously treated trees subsequently removed as dying or dead. f. newly uninfected trees treated (with incomplete ring) 1. PCNB
2. CALIXIN
g. previously treated trees retreated 1. PCNB
2. CALIXIN
h) uninfected trees treated 1. PCNB
2. CALIXIN
Monitor the progress of disease and success of treatment measures from these records at yearly intervals.
2.7 Treatment Procedures for Root Disease Control in Young Mature Rubber - Panel (BO-1). Treatment procedures during early years of maturity when the trees are still tapped on Panel A (BO-1) are more or less the same for immature rubber, but with adjustments made for the larger size of the trees. The following procedures must be observed : 2.7.1
Foliage Inspection
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Institute row-by-row foliage inspection every 1 to 3 months, depending upon the extent of incidence, to detect and mark diseased trees. Because of wintering, inspection should not be conducted from March-May but before and after this period. Trees that have the entire canopy affected are marked separately with a black “X” mark for subsequent removal together with their entire root system, as they cannot be saved. Their neighbors on either side should be treated. Signs of out of season flowers or fruiting should be looked for. These frequently signify presence of root disease. On one hand, trees exhibiting foliage symptoms on one or two branches on one side generally have a major lateral on the opposite side that is diseased. They can be protected by treatment. 2.7.2
Collar and Lateral Root Inspection
For trees exhibiting diseased symptoms, inspection must be done from the collar down to the level of the lowest lateral root to confirm the disease and assess its severity and extent. If the disease has progressed to affect more than 90% of the collar and top of the root, further effort to save that tree is not worthwhile: The trees should then be marked for removal with a black “X” mark. Collar inspection is then continued on neighboring trees on either side of the row until a healthy tree is reached. 2.7.3
Exposure of Base of Tap Root and Laterals
The soil around the bole to a radius of 35 - 45 cms should be opened to expose the base of laterals and top of tap root of the trees marked for treatment, infected as well as the healthy trees immediately next to them. 2.7.4 Inspection to Demarcated Diseased Parts
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Inspect the exposed root system to assess the extent of diseased portions, by scraping small slices of superficial bark with a blunt scraper. 2.7.5 Tracing and Cutting Diseased Laterals Trace any diseased lateral to its source. This should be continued even into the inter-rows as the roots are large and legume covers already thin. In the tree rows on contour lines, inspection of affected roots from neighboring trees is to be confined only on the same row of infected trees. Cut off the diseased portion of the lateral and remove the infection source entirely, and burn it. 2.7.6 Surgical Removal of Diseased Tissues If the disease has already reached the collar, surgically remove every trace of necrotic tissue from it and from the top portion of tap root and base of laterals down to healthy wood. If the disease has progressed deeper down along the tap root, treatment may be abandoned and the tree removed (dug out and burned). In case where a large amount of root is cut away topping may be indicated or branch pruning may be necessary. Use of “ties” to keep tree upright may also be necessary. 2.7.7 Application of Collar Protectant Dressing Wipe the exposed root system clean of soil particles with a piece of cloth; do not scrape healthy roots. Next, apply the appropriate collar protectant dressing all around the collar and top 10 cm or more of the tap root to cover all areas which have undergone surgery. Apply the dressing also to the base of laterals all round up to a distance of 20-25 cm and to the cut ends of any severed laterals. Small feeder roots may be cut away before applying the dressing. CAP-PBD Post-Replanting Rubber Manual
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2.7.8 Refilling Hole Refill the hole with the same soil making sure there is no fragments of root or other diseased materials mixed in it. Pile earth up around tree base to prevent water logging, and enough to permit rain water to run off and not pool. 2.7.9 Disposal of Infected Debris Collect and burn all diseased materials, such as roots, root-fragments, pieces of bark and wood, disease sources and root system of trees removed. Marking Treated Trees Mark all treated trees with a solid black paint ring in the trunk at 1.70 meters from the ground. Mark the initials of the disease above the ring as follows: R.L = Rigidoporus Lignosus. P.N = Phellinus Noxious. G.P = Ganoderma Pseudoferrum. U.Z = Ustulina Zonata. Diseased trees that are treated get a solid line complete ring, while their healthy neighbors which were inspected and treated are given a broken- line incomplete ring at the same height. Paint the month and year of treatment just above the ring. 2.7.10 Re- Treatment Open back the soil around collar of all treated trees after two years for any new infection and retreat them, unless new symptoms appear before two years, in which case the tree must be retreated promptly
2.8 Treatment Procedures for Root Disease Control in Mature Rubber.
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Control of root disease in mature rubber older than those being tapped on Panel A (BO-1) is difficult and prohibitively expensive. Nevertheless, some limited treatment can be justified in high yielding blocks that have a good stand. The procedures adopted for reducing tree losses comprise localized eradication of diseased material and isolation of affected areas of the field by digging isolation trenches. 2.8.1 Tree Inspection A row-by-row inspection is made every six months, to identify dead trees and marking them. 2.8.2 Disposal of Dead and Dying Trees Remove all dead and dying trees with their entire root system as well as any sources of infection traced through them. All infected root materials should then be collected and burned. 2.8.3 Collar and Lateral Root Inspection Inspect the collar and lateral root bases of the two trees on either side of the eradicated tree in the same row. If any of them is found infected, the tree next to it is collar inspected until a healthy tree is found. The soil around the tree should be dug out until the base of laterals are exposed for inspection. 2.8.4
Digging Isolation Trench
A simple isolation trench is dug midway between the last diseased tree and its immediate healthy neighbor at both ends, cutting across the planting row. If any infected roots are discovered in this trench, it is abandoned and a fresh one dug that includes that healthy tree as well. Isolation trenches are dug 30 cm wide and 60 cm deep. CAP-PBD Post-Replanting Rubber Manual
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2.8.5 Extension of Isolation Trench Extend the simple trench, to half the width of the inter-row on either side. Infected trees coming within the trench are tapped until they start dying, after which they are removed and burned. 2.8.6 Completion of Isolation Trench If many trees in a row or more than one adjacent row are affected, the trenches across the rows are connected to enclose the entire effected area by digging a trench lengthwise along the middle of the inter row on either side. Figure (b) below. (a)
(b)
X
X
X
X
X
X
X
X
X X
2.8.7 Disease Patches Small disease patches if any, are also enclosed in an isolation trench around the patch, constructed as in figure (a) above. However, this may become prohibitively costly for medium and large patches, a decision should be made based on calculated benefits and costs on whether to proceed or not. 2.8.8 Maintenance of Isolation Trench Isolation trenches should be inspected every twelve months to dig out any soil that may have eroded in, so that the correct width and depth are maintained, and any roots going through are severed and removed.
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2.8.9 Treatment of Wind Damage Promptly attend to trunk snap and branch breakages resulting from wind damage, to avoid spore infection of cut ends especially by brown root disease. Prune them to a slanting clean surface and apply a wound dressing containing coaltar fungicide such as 20% Izal in bitumen emulsion. 2.8.10 Treatment of USTULINA For treatment of Ustulina trunk collar and root rot, cut away all diseased tissues from the base of the trunk, collar and affected portion of the roots until only healthy tissues are exposed, and cover the wound with the above dressing. The hollow of the collar resulting from the extensive surgery may sometimes need reinforcement with cement for the tree to stand strong winds. 2.7.11 Root Disease Records It is important to keep a complete record of disease incidence and treatment for each block, with the following information enumerated after each round of inspection and treatment: a) Dates and locations of infection and treatment. b) Number of trees collar inspected. c) Trees confirmed infected after collar inspection. (invariably to be removed sooner or later). d) Number of trees showing foliage symptoms. (invariably to be removed)
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