Thursday, January 30, 2014

Fruit Fly Outbreak - Update 1/2/2014

FRUIT FLY OUTBREAK AT SELLICKS BEACH

Immediately report any maggots found in fruit directly to PIRSA Plant Health on 1300 666 010.

Respect South Australia’s strong quarantine laws and make sure your transport company, contract pickers and seasonal staff are aware that there is the potential they could spread fruit fly accidentally.

Yesterday afternoon Drew Noon, Tom Harvey from MVGWTA and myself met on your behalf with representatives from Biosecurity SA full information will follow as they update their website but we wanted to get this information out quickly. Grapes are a relatively poor host of Fruit Fly. There is only a low risk of our activities transmitting them.

It is mostly good news. While the Fruit Fly outbreak will last a minimum of 12 weeks  and fresh Fruit Fly finds are possible - all growers can harvest their grapes as normal with the following provisos;

    1. There are approximately 50x growers in the 7.5km suspension zone, the boundary is approximately Almond Grove Rd, Colville Rd, Flour Mill Rd, Port Willunga Rd and 5x growers in the 1.5km quarantine zone. Please see the attached photo of the map. A high quality version of this will be put up on the  BiosecuritySA website shortly. If you are in the 7.5km zone you will be getting this information from Biosecurity SA in the next few days in the mail. MVGWTA will also try to contact you through their database.

    A high resolution map will be available shortly.

    The 5x growers in the quarantine zone will be able to harvest their fruit and will have routine baiting on their vineyard posts. If you are in the 1.5km zone Biosecurity SA will be letting you know in person next week.

    2. Growers  within the 7.5km radius of the Fruit Fly will need to obtain a permit from the Chief Inspector. This can be done in advance. You will be able to do this  in person from the  Fruit Fly Management Office which is being set up at the Aldinga Council depo on Lacey Crt, Aldinga – 9-5pm or by ringing the Fruit Fly Hotline - 1300 666 010.

    3. It is important that your grape carriers are aware of the quarantine zone and the need for the fruit to be covered. With most harvest just starting now and ramping up over the next couple of weeks they need to make sure they have provisions to cover bins or bulk loads. Consider using shade cloth as it will stop any flies leaving your grape load while being easier to handle than tarpaulins. In the Riverland they are successfully using shade cloth.

    4. Harvesters are recommended to be washed out when they leave the quarantine zone to prevent the chance that Fruit Fly travel too. This can be done with a hose.

    5. We are going to prepare an A4 sheet with this information that will come  up with the next CropWatch McLaren Vale on Thursday. It will also have a sheet you can copy and stick to your grape bin and give to your carrier, just the facts for them to be aware of.

    It will be good practice  for your winery to process fruit from the 7.5km suspension zone quickly or store it on a hard pad. i.e limit the chance of any maggots falling out into the ground and pupating. Winemaking is  not affected.

Good news, just a little bit more work and care needed but this won’t stop your normal harvest.

Thanks also to Ben Lacey and Belinda Bramley for their work behind the scenes.

Friday, January 17, 2014

Sunburn and heatstress #v14 - UPDATE 17/1/2014



South Australia is recovering from a heatwave similar to what was experienced in autumn 2008 and spring 2009. Peak maximum temperatures recorded at  Langhorne Creek's central weather station were been 44.4oC, five days in a row were above 40oC, and night time temperatures did not cool vines down with the temperature staying above 25oC from the 13th to 16th. The McLaren Vale Wine Region had peak temperatures above 43oC. Temperatures were also over 40oC in the Adelaide Hills, Clare and the Barossa.

All of these temperatures are higher than the maximum temperature for a grapevine and they shut down most of their ripening and functions accordingly.

Above: Heat map 16th January 2014.


Each of our previous recent heatwaves had different consequences for our grapevines depending on what stage of the growing season they occurred. The November 2009 spring heatwave during flowering (EL-19 to 25) reduced berry set and yield. The March 2008 autumn heatwave interfered with ripening (EL-39) causing vines to panic ripen and affected fermentation. Our current heatwave has occurred as vineyards are going through Veraison (EL-35). Grapes become more susceptible to heat damage and sunburn as they soften and this is the biggest risk to your fruit from this week’s weather. 

Look also for leaf loss and defoliation. Most vineyards have lower leaf yellowing and some premature leaf loss.

Above: Shrivel in Langhorne Creek Cabernet Sauvignon. Unfortunately Cabernet is sensitive to heat stress. This may not directly affect fruit quality but it will affect fruit quantity.

Above: Defoliation from toxic levels of salt - 17/1/2014. This is a serious plant health issue.


Above: Cooked  Shiraz McLaren Vale South Australia - 15/1/2014. Grapevine bunches in direct sunlight or partial shade get much hotter than the surrounding air temperature. The temperature inside the bunch spikes to over 60oC and berry cells breakdown ‘cooking’ the fruit.
The three symptoms above have been seen already, with sunburn particularly in vineyards on light sandy soil where the ground reflects heat back into the grapevine canopy, salt around treelines and shrivel in sensitive varities. Fruit on both the eastern and western sides of canopies has been burnt.

At this stage yield loss varies from less than 1% to greater than 15%. Revise your yield estimates if necessary. 


HEATWAVE RECOVERY

 

What to do DURING the last days of the heatwave: Apply irrigation to maintain soil moisture at a level that enables vines to regain their turgor overnight in preparation for the next hot day.

What to do AFTER the heatwave: Irrigate to replace lost soil moisture and decrease soil temperature. Monitor for diseases that may have exploited damaged berries. Unfortunately if we get rain before harvest sun damaged berries can become infected by botrytis and other rots.

DISEASES & PESTS 

 

Understandably heatwaves naturally control mildew diseases and insect pests. It is simply too hot on the outside of grapevine canopies for them to survive. It doesn’t complete kill all problems though. It may come as a surprise but active Light Brown Apple Moth and Powdery Mildew have been found inside tight bunches this week. Powdery has established colonies earlier in the season while Light Brown Apple Moth caterpillars are able to burrow away from the heat. Both are shielded from the temperatures inside tight bunches. It is not possible to get coverage into tight bunches now and any active pests or disease inside bunches can’t be controlled.


Above: Powdery Mildew on unset fruit.
Be aware that if more hot weather occurs, more vine damage is likely. Deep irrigation and allowing your grapvines to recover at night will be vital.

Tuesday, January 7, 2014

Sulphur burn - UPDATE 7/1/2014

Above: Some sulphur fungicide burn from a Shiraz vineyard sprayed during the hot weather. Note the vines are still growing very rapidly.
When applying powdery protection avoid spraying wettable sulfur at high temperatures (35oC) when the humidity is above 70% within 24 hours of spraying.
Above: Sulphur burn on Frontignac.
Growers can opt to use the fungicide Legend (Active Ingredient: quinoxyfen, Fungicide Group: Group 13) in hot weather to avoid sulphur burning. This allows them to keep up the powdery mildew protection on their vineyard. Legend has a 45 day Withholding Period (Vintage 2014). Legend costs $24.40 per hectare at its maximum rate (20ml/100lts) assuming a 1000lt dilute spray volume (DSV).