Adelaide Hills Crop Watch 240909

CropWatch 1-2 LEAVES EL 7 Heavy Rain and Hail – What effect on vines? The most advanced blocks checked this week were at Balhannah where Chardonnay was 2-4 Leaves emerged (EL 8-11) with 5-10 cm shoots and Forreston which is slightly behind with 3-5cm shoots. Unfortunately blocks with shoots of 5-10cm are susceptible to hail damage (right). If your vineyard had hail on Monday check for damage.

Downy Mildew - low risk from the rain. During the night of the 17th of September conditions were marginal for a 10:10:24 Downy Primary event in the Adelaide Hills. Downy Mildew needs unprotected foliage to infect vines. Currently most vineyards do not have significant canopies and foliage to harbor the disease. We are entering the high-risk period when shoots are 10-30 cm long in the lead up to flowering. Leaves of any size are susceptible to infection but the larger the amount of unprotected foliage, the higher the risk. Downy mildew begins from spores (oospores) in the soil. The wet soil from recent rains has primed the oospores to activate infection readily if sufficient foliage is exposed when the 10:10:24 rule of thumb conditions occur – that is, when = 10 mm rain falls in 24 hours while temperature is = 10°C.

This message from Adelaide Hills CropWatch was compiled for the week ending Friday, September 25th 2009 and will be updated prior prior to October October 2nd. More Pest and Disease information is available at www.adelaidehillswine.blogspot.com

Leaf Botrytis

– Leaf Botrytis can develop in vines that have been damaged by earlier hail and wind – as shown above. This can be common in seasons where we have windy and wet weather in spring. Further rain increases leaf botrytis infections, while dry conditions help heal it up. Leaf botrytis is very easy to monitor for because it is easy to see. Many growers worry because of its obvious nature. The good news is unless the leaf botrytis spreads onto the stems or inflorescences no crop is lost. Monitor closely for spread.

1 CropWatch SA Adelaide Hills is a service provided by service provided by the Adelaide Hills Wine Region Inc. DJ’s Grower Services provide vineyard monitoring data, interpret weather data & compile the messages. Information is general in nature. Always seek professional advice specific to your vineyard. All photos (c) James Hook, Richard McGeachy & Peter Magarey unless noted. CropWatch acknowledges the support of James Hook & Matthew Wilson in preparing this message.

Powdery Mildew Preventative spray programmes should begin when vines are 2-3 weeks past bud burst that is when shoot lengths are approaching 15-20cm. The earliest vineyards will be close to this level next week. Powdery infections comes from two sources - flag shoots and cleistothecia. Cleistothecia are small fungal fruit-bodies that contain microscopic ‘seeds’ (called ascospores). Ascospores are released during mild weather (>10°C), and are triggered by 2-3mm or more rain. As the canopy develops these spores spread and infect unprotected foliage. Flag shoots grow from buds infected with disease last season (right). If you have flagshoots, careful monitoring over the next couple of weeks will help locate them. Look for stunted shoots with upward curled leaves and grey-spore growth on the stems and leaves. Good early season control of powdery mildew is important as we enter this critical period for disease development on grapevines. Remember that good spray coverage is crucial. Right: A powdery mildew flagshoot. These have been found in vineyards with previous powdery problems. Check any parts of your vineyard with a powdery history. More pictures available on the blog.

Weevil

Damage – Some weevil damage has been seen in the Southern Adelaide Hills. These pictures were taken this week in Kuitpo – south of Meadows.

Look for buds that have been hollowed out as shown left. Garden Weevil shown below can be very destructive. Monitor now.

CropWatch SA Adelaide Hills is a service provided by service provided by the Adelaide Hills Wine Region Inc. DJ’s Grower Services provide vineyard monitoring data, interpret weather data & compile the messages. Information is general in nature. Always seek professional advice specific to your vineyard. All photos (c) James Hook, Richard McGeachy & Peter Magarey unless noted. CropWatch acknowledges the support of James Hook & Matthew Wilson in preparing this message.