Talendo on Powdery Mildew - UPDATE 5/2/2013

We always say prevention is better than cure, but can late season powdery applications get you out of trouble?

Above - The photo above of powdery mildew was taken on the 5th of January. An infection of powdery has affected all of the ‘shot’ berries. It shows you that disease was very active 4-6 weeks ago and powdery is very good at finding a way to infect fruit. This is in an otherwise well tended and healthy VSP vineyard with an open canopy. At this point the grower applied the registered powdery mildew fungicide Talendo^tm, Proquinazid, GROUP 13 FUNGICIDE.

Above - February 5^th powdery in the same vineyard. Note the dark brown / black discolouration on the infected berry. The powdery is not actively spreading.

The 2012/13 season has experienced low to moderate powdery mildew pressure. Levels are generally very low. 

At this time of year, the focus of powdery mildew management should be on reducing inoculum production for next year. In January and February, the fungus switches to producing overwintering structures called cleistothecia. They can be seen as small, yellow, brown and black specks on the surface of the powdery colonies. 

While mature cleistothecia are generally not affected by fungicide sprays (except by drenching).In some cases significant powdery mildew detected earlier in the season has been controlled by growers applying late season agrochemical sprays and dry, hot weather. 

In one case the new fungicide Talendo was tried.

In this case the grower was lucky!

Prevention of disease is always better than trying to cure established infections. Early season control is the key to managing powdery mildew. What is applied after EL-33 Berries Peasize is a last ditch attempt to stop visible symptoms and limit cleistothecia.

All chemicals currently registered for this disease, Talendo included, are best applied before infection. A preventative spray program reduces the risk of disease development and damage but increases the number of sprays needed for disease control. What Talendo does have the advantage of is it is new chemistry compared to other late season agrochemicals from the DMI group, consist of the fungicides Bayfidan, Mycloss, Rubigan, Topas. Resistance has not yet developed in the powdery fungus to limit its effectiveness.