Chapter 8 A
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Chapter 8 A as PDF for free.
More details
- Words: 4,158
- Pages: 16
Field Maintenance Guidelines For Mature Rubber Area
3.
Panel Diseases Control 3.1 Introduction In the past several years there has generally been an increase in stem diseases largely due to the planting of high yielding rubber cultivars regardless of their susceptibility to diseases. As a result several modern clones, some recommended for planting, are highly susceptible to one or other important stem diseases. Some of the notable panel diseases known to day includes: Black stripe, Mouldy rot, Brown Bast, Bark Necrosis, Stem die back, Pink Disease and Patch Canker,
3.2 Black Stripe Disease The causal organism for this disease is Phytopthora palmivora and unless properly controlled, Black stripe will become a very serious panel disease. It is entirely a disease of the tapping panel, and tapping surface may become so badly injured and disfigured that the renewed bark becomes difficult to tap. Symptoms: The early stage of the disease is characterized by the appearance of fine, black vertical lines on the tapped bark just above the tapping cut. These lines are first parallel to one another but as the disease progresses they fuse and form a cankerous condition resulting in the formation of large depressed areas in the cortex above the tapping cut. The disease will also extend into the untapped bark below the tapping cut. The black lines are wood vessels that the pathogen has invaded and along which it can grow under the virgin bark and renewing tapping panel, producing splits and cankers in the overlying barks. The cortex is destroyed down to the wood. New growth can take place only from the edge of the wound, hence lesions become bordered by swollen callus. Methods of Control:
CAP-PBD Post-Replanting Rubber Manual
84
Field Maintenance Guidelines For Mature Rubber Area
Preventive measures consist of covering the renewing bark with 2% Difolatan 4F solution in water or 1% solution of 80% WP after each tapping until control is achieved. If preventive measures have failed, infected trees should be immediately taken out of tapping until wet weather has stopped, and then diseased areas scraped back to healthy tissues, and disinfected with Difolatan. The infected scrapings should be burned.
3.3 Mouldy Rot Mouldy rot is a disease of a tapping panel which occurs in the wet season; when present Mouldy rot can cause severe injury. It is more prominent in areas where the atmosphere is continuously damp, owing to close planting and density of undergrowths. The causal fungus, Ceratocystis fimbriata, is unable to thrive in conditions of low humidity, and the diseases usually disappear with the advent of dry season. Symptoms: The disease first appears as dark depressed spots on the tapping panel, from 0.25” to 1” above the tapping cut, which unite to form a continuous sunken band parallel to the cut. The course of the disease is rapid, and the sunken band becomes covered with a greyish mycelium which is easily seen from a distance. In a few weeks after infection the diseased tissues rot completely, exposing discolored wood. An extensive wound, often resembling bad tapping, is the result. Method of Control. Proper weeding will permit more air circulation, thus preventing the necessary conditions of high humidity for the spread of this disease. Cessation of tapping during periods when the disease is active gives complete protection, as the fungus is only able to infect newly tapped bark. A change to third or fourth daily tapping reduces the incidence considerably. (The temporary adoption of a 15 to 21 day periodic system has even more effect, but this must be authorized by top management).
CAP-PBD Post-Replanting Rubber Manual
85
Field Maintenance Guidelines For Mature Rubber Area
The disease is spread by insects and air currents, and once started is also spread by tapper's knives and clothing. For this reason it is essential that tappers are not alternated between infected and uninfected tasks, and that their knives be immersed in a disinfectant solution between trees (2% Formalin in water). The superficial nature of the growth of this fungus makes the disease amenable to treatment by fungicides, provided that a suitable fungicide is applied systematically. A suitable aqueous fungicide is .02 % Benlate; up to 12 applications, made after each tapping, may be required for control. Actidione 4, 2, 0.5% or Derosal 60 WP, 1% may also be used.
3.4 Brown Bast Brown Bast is a condition only of trees which have been over-tapped. It is the expression of a derangement in the laticiferous system, brought about by excessive exploitation.
CAP-PBD Post-Replanting Rubber Manual
EXHIBIT 10:6:Typical EXHIBIT TypicalSymptom Symptom ofof thethe Advanced Stageof of Brown Brown Bast Disease. advanced stage Bast disease.
86
Field Maintenance Guidelines For Mature Rubber Area
Symptoms. The first obvious symptoms are a reduction in yield and a drying-up of a part or whole of the tapping cut. The affected cortex becomes succulent and watery, and on scraping a dark discoloration is visible in its inner layer. The discoloration may be seen to extend downwards into the untapped cortex and sometimes upwards into the renewing bark above the cut. If the same intensity of tapping is maintained, the panel may eventually dry up completely; the dry part of the bark dies, giving rise to wound reactions leading to extremely rough and irregular wood and bark formations. Method of Control. Preventive measures consist of planting clones that have been proved to be not highly susceptible and of adopting a moderate tapping system (67% intensity) on clones known to be susceptible. Trees which show early signs of Brown Bast should continue to be tapped regularly as the partially dry cut serves to reduce tapping intensity and the damaged bark will gradually be cut away. If the symptoms persist or become worst and there is evidence that the disease is spreading, the extent of the damage should be ascertained by pin pricks and an isolation groove, to the cambium and should be around the dead bark. This dead bark should then be scraped off nearly to the cambium to promote more rapid regeneration of new bark. The tree should be rested for three months to permit the build-up of food reserves to normal levels, after which tapping may be resumed at a reduced intensity.
CAP-PBD Post-Replanting Rubber Manual
87
Field Maintenance Guidelines For Mature Rubber Area
This may be accomplished by marking the tree and reducing the length of the cut to 1/3 S if it is being tapped ½ S d2, or by not applying stimulant if it is on ½ S ,d/3.Stimulant should never be applied to trees with any degree of Brown Bast. If the panel dries right down to ground level and shows no sign of recovery after rest, a new cut should be opened on the opposite side of the tree at the time of normal panel changeover. If a tree becomes totally untappable through Brown Bast, it should be removed to eliminate a potential source of disease and to reduce the competition for soil nutrients, water and sunlight.
3.5 Bark Necrosis A necrosis on bark is different from the one on the panel. The term bark necrosis is applied to a range of symptoms starting with degeneration of the untapped bark anywhere over the trunk while panel necrosis is found on the opened tapping cut and the panel guide lines. Panel necrosis is frequently noticed in newly opened tree as well as on the trees which have been in tapping for some time and also in spout wounds. Newly opened panel B often suffers from Bark Necroses Both panel and bark necrosis may be present at the same time on a single rubber tree. Both usually occur during wet weather. And both, if not properly controlled, may also lead to tree dryness and further disease development of ustulina stem rot and borer beetles. From a study carried out on the necrotic bark, species of Phytophtora, Fusarium and Colletotrichum as well as some bacterias were found. No conclusive evidence of any one of them being solely responsible for the malady, however, has been determined. Panel necrosis may be caused by Fusarium solani and/or Botryodiplodia theobromae, because both fungi are common saprophytes on the bark. Symptoms. The symptoms noticed vary at different stages of the disease, often giving the impression that more than one disease may be present. It starts in the
CAP-PBD Post-Replanting Rubber Manual
88
Field Maintenance Guidelines For Mature Rubber Area
inner bark tissues but close observation during wet weather or in the early morning when the bark is still moist may reveal the outline of affected patches externally. Cracks in the bark are then accompanied with light bleeding, and often the trees have been gone dry already. However, in most instances the lower part of the trunk below the tapping cut is a site of infection, suggesting that the cut may be the starting point which makes for confusion with panel necrosis. When the upper part of the stem beyond the panel height is attacked, it may appear to start from the fork and spread downwards spirally following the latex vessels or go up from the tapping cut. The disease nevertheless, can occur independently on the tapping cut or the fork anywhere on untapped bark of the trunk right down to the collar. Detection Detection as early as possible is essential because the disease spreads very rapidly under wet conditions, frequently in a spiral accompanying the vascular system of the trunk in all directions, to cover a substantial portion of the trunk in a few days. A regular, periodical tree to tree inspection of each block in tapping must therefore be organized in order to detect the infected trees as early as possible. Tappers and tapping capataz should report BN in its earliest stage. A tree-to-tree inspection, however, will be a labor consuming operation. Such an operation must depend partly on the tapper's daily observational reports which must be made by them as an additional and compulsory responsibility. When such a report has been reviewed and confirmed by a special crew which is assigned to the task, a treatment using the recommended fungicides must be carried out at once. In checking any trees under suspicion, a short metal scraper must be used to scrape the outer bark, which if diseased, will reveal the spreading
CAP-PBD Post-Replanting Rubber Manual
89
Field Maintenance Guidelines For Mature Rubber Area
necrosis in the cortex. Scraping off the diseased part must be done lightly so as not to destroy the cambium. In this case, a sharp and light scraper must be used. The affected patches will show moist tissues with dirty purplish red or reddish brown color. Normally, dry weather conditions for few days will help the affected trees heal by themselves as the dead cortex will gradually dry up and scale off, followed by bark regeneration, and recovery of the tree. On the other hand when the weather is wet, the conditions are favorable for the disease to spread and if a tree remains too long without treatment the cambium may be also affected resulting in profuse bleeding and large wounds, and dry trees. Hence prompt treatment is important. As soon as a block or an area within a block, has a substantial number of infected trees, then all the trees in the areas must be sprayed promptly with a mixture of 2% Difolatan and red dye. This will greatly assist in preventing the spread of the disease. The tree is sprayed once only up to a height of 2.5 metres. Treatment. As soon as the disease is detected, the tree must be taken out of tapping, according to the following criteria.
When 25% of the tapping cut has become necrotic, the tree must rest from tapping for two weeks.
When a tapping cut shows 25% to 50% necrosis, the tree should be put on rest for one full month.
When there is 50% to 75% necrosis on the tapping cut, the tree must rest for three months.
When the necrosis has covered more than 75% of the tapping cut, the tree must rest for six months.
When the bark necrosis is found away above the tapping cuts, the trees need not rest from tapping.
All infected patches of bark, and the surrounding healthy tissue must be painted with a 4 % solution of Calixin in Palm Oil, plus red dye, and
CAP-PBD Post-Replanting Rubber Manual
90
Field Maintenance Guidelines For Mature Rubber Area
Thiodan 0.5% (other chemical fungicides which may have a good curative effect on BN are Bayleton, Bayfidon and Derosal. The mixture have to be applied promptly, with a paintbrush. Trees must be marked with a large white X, (40 cms) plus the letters B.N., and the date. After 30 days the mixture should be re-applied and continued at 30 day intervals until the tree is healthy again and producing well. Basically 2 3 rounds should be sufficient. In cases where infection has become severe, before detection, and the bark is rotten, then the rotten bark must be removed and burned to ashes. The resulting scraped area of the trunk will have Calixin and Thiodan painted on, and then be sealed with grease, as soon as the panel is dry. Preparation of Mixture For 1 litre of solution, take 960 gram of Palm Oil and place in a container and melt. After melting, add red dye and stir well. Add 40 cc of Calixin 75 EC and 7.5 cc Thiodan while stirring vigorously. This solution is then ready to use. The mixture should be well mixed prior to use. Secondary Problems The bad odor of rotting bark will encourage borer beetles (Xyleborus spp) to come. The borer beetles will eat up the wood part of the tree by drilling holes or tunnels. The tunnels are also used to lay their eggs. When the eggs have hatched, the larva will also become wood-eaters like the adults. The adults are mobile insects, moving from one hole to another and in fact from one tree to another tree. The borer beetles besides destroying the wood as well as bark will also act as a carrier of ustulina mycelium. The mycelium which may stick to the thick and rough skin of borer beetles may be carried over from one sick tree to infect another tree which has just attacked by beetles, thus carrying the ustulina mycelium thru borer beetles.
CAP-PBD Post-Replanting Rubber Manual
91
Field Maintenance Guidelines For Mature Rubber Area
This is evident because in every hole drilled out the ustulina mycelium will develop in the wood tissues around the holes. With the presence of ustulina, the wood tissues will become rotten, making the plant more susceptible to breakage during windstorm.
EXHIBIT EXHIBIT11: 7: Stem StemUstulina Ustulina disease Diseaseof ofRubber Rubber
Thus, as the population of borer beetles increases the possibility of a spreading attack of ustulina exists. The affected area, when not properly controlled, is often invaded by borer beetles. The fungus then penetrates the wood right across the stem or main branches. Thus, the appearance of the tree may cause confusion with ustulina disease. Ustulina is confirmed when a number of fructifications develop on it as plates, which later turn grey-black or charcoal and grow into a contiguous sheet covering a large portion of the wound. Points to Remember: a.) Since wet weather will make conditions more favorable for the necrotic infection to spread, the field must always be kept clean especially in the
CAP-PBD Post-Replanting Rubber Manual
92
Field Maintenance Guidelines For Mature Rubber Area
area where the outbreak of the disease is found, and checks for this disease should be routinely made during the wet season. b.) As a preventive measure, monthly tapping panel dressing using a fungicidal formulation may be recommended where we get frequent occurrence of Bark Necrosis. Preventive spraying of the panel is necessary in attacked areas c.) All wind snapped trunks and broken branches must be treated immediately by cutting off the broken edges and applying grease to the wound surface.
3.6
Stem Die Back
Die back is a term used to designate those disease characterized by a progressive dying back of the young shoots. Generally they are caused by fungi that penetrate the tender tissues; the progressive die back being evidenced as the mycelium advances within. The same fungi may also penetrate the “snags” of dead branches or of cutback grafts. Penetration of grafts at the union may also occur. This condition is found more in transplanted buddings than in field budded rootstocks. The fungi known to be capable of producing die back are: Botrydiplodia theobromae. Gloeosporium spp. Fusicladium spp. Colletotrichum sp. Phyllosticta sp. It is difficult to determine the causal organism from visual inspection only, particularly if the affected portions have been dead for some time. The diseases are spread by wind blown spores. Clones, AVROS 2037 and GT-1 are both quite susceptible to die back, usually at about 3 - 5 years of age or may even occur in mature rubber. Symptoms Top die back is easily observable. If the infection is terminal, there is a progressive blackening and dying of the shoot downwards, which often CAP-PBD Post-Replanting Rubber Manual
93
Field Maintenance Guidelines For Mature Rubber Area
ceases spontaneously, but may continue to the base of plant, killing it completely. In older trees dead branches or “stag heads” may be seen frequently on the tops of the trees. These are old cases of die back which the tree has been able to throw off spontaneously. Method of Control Top die back on young grafts may be treated successfully by pruning, the cut being made one to two feet below the effected part, (mainly all stumps). In the field the disease is generally found in patches, and early discovery and treatment are essential for the spread of the disease to surrounding trees may be rapid. Plants sometimes are killed to the ground within a week, though others may resist the disease to such an extent as to recover spontaneously before the disease has proceeded very far. All pruning must be burned immediately to prevent dissemination of the spores. Old trees possess more resistance, and the pruning of stag heads is not worth the labor of reaching them. The appearance of subsequent cases must be looked for in order to prevent a recrudescence of the trouble. Spraying with a Berthoud sprayer using Difolatan 1% controls die back but is not always feasible due to terrain and constraints on the availability of equipment.
3.7 Pink Disease. Pink disease, caused by the fungus Corticium salmonicolor, is typically a disease of the trunk. It is found in most tropical regions on a wide variety of plants, both wild and cultivated. Symptoms The disease usually appears at or near the forks of the branches as a white or pink encrustation of interwoven mycelium, generally encircling the branch.
CAP-PBD Post-Replanting Rubber Manual
94
Field Maintenance Guidelines For Mature Rubber Area
Extended periods of wet weather appear to be necessary for development of the disease, and consequently under local condition its appearance is noted almost entirely at the end of the wet season. By this time the fungus penetrates the cortical tissues to such an extent that the food supply of the branch is cut off and it dies. It is at this time that the disease becomes very noticeable, because the contrast of the branch with its dead leaves against the healthy green of the rest of the tree attracts attention. Sometimes the fungus is located at the origin of the main branches, in which case the whole crown dies. With the advent of the dry season, the bark killed by the fungus breaks open, becoming dark in color. The fungus by this time has produced spores, which remain dormant until moist conditions prevail, when activity may be renewed. New shoots are produced on the stem, below the attacked area. Frequently, exudation of latex may be observed during the active stage of the disease. Method of Control The essential factor in preventive measures is the reduction of inoculum, that is, the amount of spores which may be blown about by the wind. This requires detection of the disease in its early stages. During wet weather, weekly detection rounds must be made on all immature rubber between 2 - 5 years of age. In older rubber, detection should also be weekly, when there is evidence of a severe attack of pink disease. Dead crowns are a sign of total failure to control the disease. If the fungus has not girdled the branch but extends over a small area of bark only, it may be possible to save the branch as a whole by scraping the diseased portion away and immediately painting or spraying the resulting wound with Calixin 2% RM.
CAP-PBD Post-Replanting Rubber Manual
95
Field Maintenance Guidelines For Mature Rubber Area
All diseased material removed should be burned. Very often it will be found that the branch has been completely girdled before detection. In this case the only treatment is immediate pruning of the diseased branch at least one foot below the lowest visible sign of the fungus. Calixin RM should then be applied to the diseased stem section to prevent the further spread of inoculum. Pruning of the new shoots to leave the strongest one will be necessary later. All pruned surfaces should be painted with coaltar and diseased branches burned as soon as possible.
EXHIBIT ofof Rubber EXHIBIT12: 8:Stem StemBleeding BleedingDisease Disease Rubber
CAP-PBD Post-Replanting Rubber Manual
96
Field Maintenance Guidelines For Mature Rubber Area
3.8 Patch Canker. This disease, associated with species of Phytophtora and Pythium is widespread on all plantations and may be particularly prevalent on the budded areas in tapping. The disease may occur anywhere on the stem, but is generally confined to the panel and basal area where mechanical wounding by spouts, hanger wires or seeding tolls is likely to occur. Symptoms Frequently the first obviously visible sign of the disease is the appearance of a group of small holes in the black. These are made by small borers attracted by the diseased tissues. The bark over the diseased patch breaks open, exposing cortex of a reddish brown color. This color changes to black when exposed to air. Extension of the diseased area depends upon moisture conditions; it may be rapid during the wet season, when old patches may be seen surrounded by a developing callus with an area of exposed wood in the center. On examining patches which are still active, plugs of coagulated latex may be found. Unless appropriate treatment is applied, diseased patches may continue to widen over a considerable area, especially during wet periods. After a period of quiescence during the dry season, they may start into activity again with the onset of the rains. Method of Control All disease tissues, recognized by their discoloration, should be excised until the patch is completely surrounded by healthy tissues. This can be ensured by continuing the excision until minute drops of latex exude from the surrounding cortex; the diseased cortex will yield no latex. Excision should then be continued until the area is completely surrounded by one inch of healthy bark. All scrapings should be carefully collected in a container and burned to ashes.
3.9 Reports and Records. Capataz Report CAP-PBD Post-Replanting Rubber Manual
97
Field Maintenance Guidelines For Mature Rubber Area
The capataz of each disease control gang will submit a daily report to the Assistant, showing the number of trees inspected and treated. Assistant's Monthly Disease Report A monthly report, which is compiled from the capataz's daily report, will be submitted to the Field Manager. Disease Control Gangs Labor Each year sufficient labor should be budgeted to carry out disease control measures. Estimates of labor required are the responsibility of the Production Manager, together with his Assistants.
3.10
Equipment.
Disease control gangs should be equipped with the utensils necessary to carry out various control measures. Such equipment will normally comprise: Scraping tools, knives, pruning saws, sprayers, dusters, etc. Safety equipment such as gloves, safety glasses recommended where toxic chemicals are being used.
are
strongly
3.11Marking Treated Trees. All treated trees will be painted with suggested marks, as follows: Fomes RL (Coaltar) Phellinus Pn (Coaltar) Ganoderma Gp (Coaltar) Ustulina Uz (Coaltar) Pink Disease Pd (Coaltar) Bark Necrosis X (White Paint) Dryness red x, xx, xxx, xxxx, on panel (Coaltar) Wind snap date (6 months after) Brown Bast Large X (Coaltar) Girthing G (immature rubber only - Colored Paint) Scrape off old markings once the tree has recovered from the disease. Mouldy Rot
CAP-PBD Post-Replanting Rubber Manual
MR 98
Field Maintenance Guidelines For Mature Rubber Area
Black Stripe Lump Canker Die Back
BS LC Coaltar DB Coaltar
Date Date of cut back
Once a tree has recovered from the disease which affected it, it will marked with the letter “R” and the date. This should be done for every one of the above disease.
CAP-PBD Post-Replanting Rubber Manual
99
3.
Panel Diseases Control 3.1 Introduction In the past several years there has generally been an increase in stem diseases largely due to the planting of high yielding rubber cultivars regardless of their susceptibility to diseases. As a result several modern clones, some recommended for planting, are highly susceptible to one or other important stem diseases. Some of the notable panel diseases known to day includes: Black stripe, Mouldy rot, Brown Bast, Bark Necrosis, Stem die back, Pink Disease and Patch Canker,
3.2 Black Stripe Disease The causal organism for this disease is Phytopthora palmivora and unless properly controlled, Black stripe will become a very serious panel disease. It is entirely a disease of the tapping panel, and tapping surface may become so badly injured and disfigured that the renewed bark becomes difficult to tap. Symptoms: The early stage of the disease is characterized by the appearance of fine, black vertical lines on the tapped bark just above the tapping cut. These lines are first parallel to one another but as the disease progresses they fuse and form a cankerous condition resulting in the formation of large depressed areas in the cortex above the tapping cut. The disease will also extend into the untapped bark below the tapping cut. The black lines are wood vessels that the pathogen has invaded and along which it can grow under the virgin bark and renewing tapping panel, producing splits and cankers in the overlying barks. The cortex is destroyed down to the wood. New growth can take place only from the edge of the wound, hence lesions become bordered by swollen callus. Methods of Control:
CAP-PBD Post-Replanting Rubber Manual
84
Field Maintenance Guidelines For Mature Rubber Area
Preventive measures consist of covering the renewing bark with 2% Difolatan 4F solution in water or 1% solution of 80% WP after each tapping until control is achieved. If preventive measures have failed, infected trees should be immediately taken out of tapping until wet weather has stopped, and then diseased areas scraped back to healthy tissues, and disinfected with Difolatan. The infected scrapings should be burned.
3.3 Mouldy Rot Mouldy rot is a disease of a tapping panel which occurs in the wet season; when present Mouldy rot can cause severe injury. It is more prominent in areas where the atmosphere is continuously damp, owing to close planting and density of undergrowths. The causal fungus, Ceratocystis fimbriata, is unable to thrive in conditions of low humidity, and the diseases usually disappear with the advent of dry season. Symptoms: The disease first appears as dark depressed spots on the tapping panel, from 0.25” to 1” above the tapping cut, which unite to form a continuous sunken band parallel to the cut. The course of the disease is rapid, and the sunken band becomes covered with a greyish mycelium which is easily seen from a distance. In a few weeks after infection the diseased tissues rot completely, exposing discolored wood. An extensive wound, often resembling bad tapping, is the result. Method of Control. Proper weeding will permit more air circulation, thus preventing the necessary conditions of high humidity for the spread of this disease. Cessation of tapping during periods when the disease is active gives complete protection, as the fungus is only able to infect newly tapped bark. A change to third or fourth daily tapping reduces the incidence considerably. (The temporary adoption of a 15 to 21 day periodic system has even more effect, but this must be authorized by top management).
CAP-PBD Post-Replanting Rubber Manual
85
Field Maintenance Guidelines For Mature Rubber Area
The disease is spread by insects and air currents, and once started is also spread by tapper's knives and clothing. For this reason it is essential that tappers are not alternated between infected and uninfected tasks, and that their knives be immersed in a disinfectant solution between trees (2% Formalin in water). The superficial nature of the growth of this fungus makes the disease amenable to treatment by fungicides, provided that a suitable fungicide is applied systematically. A suitable aqueous fungicide is .02 % Benlate; up to 12 applications, made after each tapping, may be required for control. Actidione 4, 2, 0.5% or Derosal 60 WP, 1% may also be used.
3.4 Brown Bast Brown Bast is a condition only of trees which have been over-tapped. It is the expression of a derangement in the laticiferous system, brought about by excessive exploitation.
CAP-PBD Post-Replanting Rubber Manual
EXHIBIT 10:6:Typical EXHIBIT TypicalSymptom Symptom ofof thethe Advanced Stageof of Brown Brown Bast Disease. advanced stage Bast disease.
86
Field Maintenance Guidelines For Mature Rubber Area
Symptoms. The first obvious symptoms are a reduction in yield and a drying-up of a part or whole of the tapping cut. The affected cortex becomes succulent and watery, and on scraping a dark discoloration is visible in its inner layer. The discoloration may be seen to extend downwards into the untapped cortex and sometimes upwards into the renewing bark above the cut. If the same intensity of tapping is maintained, the panel may eventually dry up completely; the dry part of the bark dies, giving rise to wound reactions leading to extremely rough and irregular wood and bark formations. Method of Control. Preventive measures consist of planting clones that have been proved to be not highly susceptible and of adopting a moderate tapping system (67% intensity) on clones known to be susceptible. Trees which show early signs of Brown Bast should continue to be tapped regularly as the partially dry cut serves to reduce tapping intensity and the damaged bark will gradually be cut away. If the symptoms persist or become worst and there is evidence that the disease is spreading, the extent of the damage should be ascertained by pin pricks and an isolation groove, to the cambium and should be around the dead bark. This dead bark should then be scraped off nearly to the cambium to promote more rapid regeneration of new bark. The tree should be rested for three months to permit the build-up of food reserves to normal levels, after which tapping may be resumed at a reduced intensity.
CAP-PBD Post-Replanting Rubber Manual
87
Field Maintenance Guidelines For Mature Rubber Area
This may be accomplished by marking the tree and reducing the length of the cut to 1/3 S if it is being tapped ½ S d2, or by not applying stimulant if it is on ½ S ,d/3.Stimulant should never be applied to trees with any degree of Brown Bast. If the panel dries right down to ground level and shows no sign of recovery after rest, a new cut should be opened on the opposite side of the tree at the time of normal panel changeover. If a tree becomes totally untappable through Brown Bast, it should be removed to eliminate a potential source of disease and to reduce the competition for soil nutrients, water and sunlight.
3.5 Bark Necrosis A necrosis on bark is different from the one on the panel. The term bark necrosis is applied to a range of symptoms starting with degeneration of the untapped bark anywhere over the trunk while panel necrosis is found on the opened tapping cut and the panel guide lines. Panel necrosis is frequently noticed in newly opened tree as well as on the trees which have been in tapping for some time and also in spout wounds. Newly opened panel B often suffers from Bark Necroses Both panel and bark necrosis may be present at the same time on a single rubber tree. Both usually occur during wet weather. And both, if not properly controlled, may also lead to tree dryness and further disease development of ustulina stem rot and borer beetles. From a study carried out on the necrotic bark, species of Phytophtora, Fusarium and Colletotrichum as well as some bacterias were found. No conclusive evidence of any one of them being solely responsible for the malady, however, has been determined. Panel necrosis may be caused by Fusarium solani and/or Botryodiplodia theobromae, because both fungi are common saprophytes on the bark. Symptoms. The symptoms noticed vary at different stages of the disease, often giving the impression that more than one disease may be present. It starts in the
CAP-PBD Post-Replanting Rubber Manual
88
Field Maintenance Guidelines For Mature Rubber Area
inner bark tissues but close observation during wet weather or in the early morning when the bark is still moist may reveal the outline of affected patches externally. Cracks in the bark are then accompanied with light bleeding, and often the trees have been gone dry already. However, in most instances the lower part of the trunk below the tapping cut is a site of infection, suggesting that the cut may be the starting point which makes for confusion with panel necrosis. When the upper part of the stem beyond the panel height is attacked, it may appear to start from the fork and spread downwards spirally following the latex vessels or go up from the tapping cut. The disease nevertheless, can occur independently on the tapping cut or the fork anywhere on untapped bark of the trunk right down to the collar. Detection Detection as early as possible is essential because the disease spreads very rapidly under wet conditions, frequently in a spiral accompanying the vascular system of the trunk in all directions, to cover a substantial portion of the trunk in a few days. A regular, periodical tree to tree inspection of each block in tapping must therefore be organized in order to detect the infected trees as early as possible. Tappers and tapping capataz should report BN in its earliest stage. A tree-to-tree inspection, however, will be a labor consuming operation. Such an operation must depend partly on the tapper's daily observational reports which must be made by them as an additional and compulsory responsibility. When such a report has been reviewed and confirmed by a special crew which is assigned to the task, a treatment using the recommended fungicides must be carried out at once. In checking any trees under suspicion, a short metal scraper must be used to scrape the outer bark, which if diseased, will reveal the spreading
CAP-PBD Post-Replanting Rubber Manual
89
Field Maintenance Guidelines For Mature Rubber Area
necrosis in the cortex. Scraping off the diseased part must be done lightly so as not to destroy the cambium. In this case, a sharp and light scraper must be used. The affected patches will show moist tissues with dirty purplish red or reddish brown color. Normally, dry weather conditions for few days will help the affected trees heal by themselves as the dead cortex will gradually dry up and scale off, followed by bark regeneration, and recovery of the tree. On the other hand when the weather is wet, the conditions are favorable for the disease to spread and if a tree remains too long without treatment the cambium may be also affected resulting in profuse bleeding and large wounds, and dry trees. Hence prompt treatment is important. As soon as a block or an area within a block, has a substantial number of infected trees, then all the trees in the areas must be sprayed promptly with a mixture of 2% Difolatan and red dye. This will greatly assist in preventing the spread of the disease. The tree is sprayed once only up to a height of 2.5 metres. Treatment. As soon as the disease is detected, the tree must be taken out of tapping, according to the following criteria.
When 25% of the tapping cut has become necrotic, the tree must rest from tapping for two weeks.
When a tapping cut shows 25% to 50% necrosis, the tree should be put on rest for one full month.
When there is 50% to 75% necrosis on the tapping cut, the tree must rest for three months.
When the necrosis has covered more than 75% of the tapping cut, the tree must rest for six months.
When the bark necrosis is found away above the tapping cuts, the trees need not rest from tapping.
All infected patches of bark, and the surrounding healthy tissue must be painted with a 4 % solution of Calixin in Palm Oil, plus red dye, and
CAP-PBD Post-Replanting Rubber Manual
90
Field Maintenance Guidelines For Mature Rubber Area
Thiodan 0.5% (other chemical fungicides which may have a good curative effect on BN are Bayleton, Bayfidon and Derosal. The mixture have to be applied promptly, with a paintbrush. Trees must be marked with a large white X, (40 cms) plus the letters B.N., and the date. After 30 days the mixture should be re-applied and continued at 30 day intervals until the tree is healthy again and producing well. Basically 2 3 rounds should be sufficient. In cases where infection has become severe, before detection, and the bark is rotten, then the rotten bark must be removed and burned to ashes. The resulting scraped area of the trunk will have Calixin and Thiodan painted on, and then be sealed with grease, as soon as the panel is dry. Preparation of Mixture For 1 litre of solution, take 960 gram of Palm Oil and place in a container and melt. After melting, add red dye and stir well. Add 40 cc of Calixin 75 EC and 7.5 cc Thiodan while stirring vigorously. This solution is then ready to use. The mixture should be well mixed prior to use. Secondary Problems The bad odor of rotting bark will encourage borer beetles (Xyleborus spp) to come. The borer beetles will eat up the wood part of the tree by drilling holes or tunnels. The tunnels are also used to lay their eggs. When the eggs have hatched, the larva will also become wood-eaters like the adults. The adults are mobile insects, moving from one hole to another and in fact from one tree to another tree. The borer beetles besides destroying the wood as well as bark will also act as a carrier of ustulina mycelium. The mycelium which may stick to the thick and rough skin of borer beetles may be carried over from one sick tree to infect another tree which has just attacked by beetles, thus carrying the ustulina mycelium thru borer beetles.
CAP-PBD Post-Replanting Rubber Manual
91
Field Maintenance Guidelines For Mature Rubber Area
This is evident because in every hole drilled out the ustulina mycelium will develop in the wood tissues around the holes. With the presence of ustulina, the wood tissues will become rotten, making the plant more susceptible to breakage during windstorm.
EXHIBIT EXHIBIT11: 7: Stem StemUstulina Ustulina disease Diseaseof ofRubber Rubber
Thus, as the population of borer beetles increases the possibility of a spreading attack of ustulina exists. The affected area, when not properly controlled, is often invaded by borer beetles. The fungus then penetrates the wood right across the stem or main branches. Thus, the appearance of the tree may cause confusion with ustulina disease. Ustulina is confirmed when a number of fructifications develop on it as plates, which later turn grey-black or charcoal and grow into a contiguous sheet covering a large portion of the wound. Points to Remember: a.) Since wet weather will make conditions more favorable for the necrotic infection to spread, the field must always be kept clean especially in the
CAP-PBD Post-Replanting Rubber Manual
92
Field Maintenance Guidelines For Mature Rubber Area
area where the outbreak of the disease is found, and checks for this disease should be routinely made during the wet season. b.) As a preventive measure, monthly tapping panel dressing using a fungicidal formulation may be recommended where we get frequent occurrence of Bark Necrosis. Preventive spraying of the panel is necessary in attacked areas c.) All wind snapped trunks and broken branches must be treated immediately by cutting off the broken edges and applying grease to the wound surface.
3.6
Stem Die Back
Die back is a term used to designate those disease characterized by a progressive dying back of the young shoots. Generally they are caused by fungi that penetrate the tender tissues; the progressive die back being evidenced as the mycelium advances within. The same fungi may also penetrate the “snags” of dead branches or of cutback grafts. Penetration of grafts at the union may also occur. This condition is found more in transplanted buddings than in field budded rootstocks. The fungi known to be capable of producing die back are: Botrydiplodia theobromae. Gloeosporium spp. Fusicladium spp. Colletotrichum sp. Phyllosticta sp. It is difficult to determine the causal organism from visual inspection only, particularly if the affected portions have been dead for some time. The diseases are spread by wind blown spores. Clones, AVROS 2037 and GT-1 are both quite susceptible to die back, usually at about 3 - 5 years of age or may even occur in mature rubber. Symptoms Top die back is easily observable. If the infection is terminal, there is a progressive blackening and dying of the shoot downwards, which often CAP-PBD Post-Replanting Rubber Manual
93
Field Maintenance Guidelines For Mature Rubber Area
ceases spontaneously, but may continue to the base of plant, killing it completely. In older trees dead branches or “stag heads” may be seen frequently on the tops of the trees. These are old cases of die back which the tree has been able to throw off spontaneously. Method of Control Top die back on young grafts may be treated successfully by pruning, the cut being made one to two feet below the effected part, (mainly all stumps). In the field the disease is generally found in patches, and early discovery and treatment are essential for the spread of the disease to surrounding trees may be rapid. Plants sometimes are killed to the ground within a week, though others may resist the disease to such an extent as to recover spontaneously before the disease has proceeded very far. All pruning must be burned immediately to prevent dissemination of the spores. Old trees possess more resistance, and the pruning of stag heads is not worth the labor of reaching them. The appearance of subsequent cases must be looked for in order to prevent a recrudescence of the trouble. Spraying with a Berthoud sprayer using Difolatan 1% controls die back but is not always feasible due to terrain and constraints on the availability of equipment.
3.7 Pink Disease. Pink disease, caused by the fungus Corticium salmonicolor, is typically a disease of the trunk. It is found in most tropical regions on a wide variety of plants, both wild and cultivated. Symptoms The disease usually appears at or near the forks of the branches as a white or pink encrustation of interwoven mycelium, generally encircling the branch.
CAP-PBD Post-Replanting Rubber Manual
94
Field Maintenance Guidelines For Mature Rubber Area
Extended periods of wet weather appear to be necessary for development of the disease, and consequently under local condition its appearance is noted almost entirely at the end of the wet season. By this time the fungus penetrates the cortical tissues to such an extent that the food supply of the branch is cut off and it dies. It is at this time that the disease becomes very noticeable, because the contrast of the branch with its dead leaves against the healthy green of the rest of the tree attracts attention. Sometimes the fungus is located at the origin of the main branches, in which case the whole crown dies. With the advent of the dry season, the bark killed by the fungus breaks open, becoming dark in color. The fungus by this time has produced spores, which remain dormant until moist conditions prevail, when activity may be renewed. New shoots are produced on the stem, below the attacked area. Frequently, exudation of latex may be observed during the active stage of the disease. Method of Control The essential factor in preventive measures is the reduction of inoculum, that is, the amount of spores which may be blown about by the wind. This requires detection of the disease in its early stages. During wet weather, weekly detection rounds must be made on all immature rubber between 2 - 5 years of age. In older rubber, detection should also be weekly, when there is evidence of a severe attack of pink disease. Dead crowns are a sign of total failure to control the disease. If the fungus has not girdled the branch but extends over a small area of bark only, it may be possible to save the branch as a whole by scraping the diseased portion away and immediately painting or spraying the resulting wound with Calixin 2% RM.
CAP-PBD Post-Replanting Rubber Manual
95
Field Maintenance Guidelines For Mature Rubber Area
All diseased material removed should be burned. Very often it will be found that the branch has been completely girdled before detection. In this case the only treatment is immediate pruning of the diseased branch at least one foot below the lowest visible sign of the fungus. Calixin RM should then be applied to the diseased stem section to prevent the further spread of inoculum. Pruning of the new shoots to leave the strongest one will be necessary later. All pruned surfaces should be painted with coaltar and diseased branches burned as soon as possible.
EXHIBIT ofof Rubber EXHIBIT12: 8:Stem StemBleeding BleedingDisease Disease Rubber
CAP-PBD Post-Replanting Rubber Manual
96
Field Maintenance Guidelines For Mature Rubber Area
3.8 Patch Canker. This disease, associated with species of Phytophtora and Pythium is widespread on all plantations and may be particularly prevalent on the budded areas in tapping. The disease may occur anywhere on the stem, but is generally confined to the panel and basal area where mechanical wounding by spouts, hanger wires or seeding tolls is likely to occur. Symptoms Frequently the first obviously visible sign of the disease is the appearance of a group of small holes in the black. These are made by small borers attracted by the diseased tissues. The bark over the diseased patch breaks open, exposing cortex of a reddish brown color. This color changes to black when exposed to air. Extension of the diseased area depends upon moisture conditions; it may be rapid during the wet season, when old patches may be seen surrounded by a developing callus with an area of exposed wood in the center. On examining patches which are still active, plugs of coagulated latex may be found. Unless appropriate treatment is applied, diseased patches may continue to widen over a considerable area, especially during wet periods. After a period of quiescence during the dry season, they may start into activity again with the onset of the rains. Method of Control All disease tissues, recognized by their discoloration, should be excised until the patch is completely surrounded by healthy tissues. This can be ensured by continuing the excision until minute drops of latex exude from the surrounding cortex; the diseased cortex will yield no latex. Excision should then be continued until the area is completely surrounded by one inch of healthy bark. All scrapings should be carefully collected in a container and burned to ashes.
3.9 Reports and Records. Capataz Report CAP-PBD Post-Replanting Rubber Manual
97
Field Maintenance Guidelines For Mature Rubber Area
The capataz of each disease control gang will submit a daily report to the Assistant, showing the number of trees inspected and treated. Assistant's Monthly Disease Report A monthly report, which is compiled from the capataz's daily report, will be submitted to the Field Manager. Disease Control Gangs Labor Each year sufficient labor should be budgeted to carry out disease control measures. Estimates of labor required are the responsibility of the Production Manager, together with his Assistants.
3.10
Equipment.
Disease control gangs should be equipped with the utensils necessary to carry out various control measures. Such equipment will normally comprise: Scraping tools, knives, pruning saws, sprayers, dusters, etc. Safety equipment such as gloves, safety glasses recommended where toxic chemicals are being used.
are
strongly
3.11Marking Treated Trees. All treated trees will be painted with suggested marks, as follows: Fomes RL (Coaltar) Phellinus Pn (Coaltar) Ganoderma Gp (Coaltar) Ustulina Uz (Coaltar) Pink Disease Pd (Coaltar) Bark Necrosis X (White Paint) Dryness red x, xx, xxx, xxxx, on panel (Coaltar) Wind snap date (6 months after) Brown Bast Large X (Coaltar) Girthing G (immature rubber only - Colored Paint) Scrape off old markings once the tree has recovered from the disease. Mouldy Rot
CAP-PBD Post-Replanting Rubber Manual
MR 98
Field Maintenance Guidelines For Mature Rubber Area
Black Stripe Lump Canker Die Back
BS LC Coaltar DB Coaltar
Date Date of cut back
Once a tree has recovered from the disease which affected it, it will marked with the letter “R” and the date. This should be done for every one of the above disease.
CAP-PBD Post-Replanting Rubber Manual
99
