1) What to do this and next week
It looks like we have a window today for application, and after the rains over the weekend, next week looks good too. Right now, I am not too concerned about powdery mildew because it has been too cold and wet for this disease; however, next week will be nice and dry (I hope!) Thus, if you are concerned about powdery, you may need to add powdery mildew specific material (Quintec, Vivando, Torino, Luna Experience, etc) for your next application. Of course, something like Luna would be good for black rot, so, you may want to hold off until at bloom application (which may happen soon for people in the south)
Also, make sure to cover for downy mildew too. Although temperature has been low, with all the rain we received, I have a feeling downy mildew pathogen can cause infection. I would use a phosphonate material (Prophyt, Phostrol, etc) at this time of the year so that I can keep the use of a big gun (Ridomil product) for at bloom application, if needed.
As usual, please rotate mode of action (= FRAC code), and keep the use of newer materials (i.e., anything other than mancozeb, captan, zirum, copper and sulfur) to less than three times a season. Limiting the use to twice is even better! A phosphonate can be used more than 3-4 times per season, but don’t over use it either. Tank mixing a newer material with a broad spectrum material will help too. This is for management of fungicide resistance, which is the reason why I cannot recommend QoI for downy mildew any longer.
2) At bloom application
Due to the spring frost events, some of cultivar may ended up having a mix of shoots from the primary and secondary buds, thus, chances are they will bloom at different timing. Please make sure to cover for both blooms. At bloom protection is very important for so many diseases!
3) Phomopsis (note the yellow specks on the picture above)
Yes, we have seen it. The weather is too conducive for Phomopsis development this year. It would be very difficult for anyone to stop it. A good news is that unless it infects rachis or damage the shoot to the point it cannot grow, most of the time, damages from Phomopsis is not as critical than other fungal diseases, such as powdery mildew. However, it is one of more difficult to manage disease, once it gets out of hand, and it can also cause fruit rot. Please make a note (literary) of where (or which vines) you found Phomopsis this year. Chances are, you will find them again on the same spot in the future because Phomopsis resides in old infected cane and cordon tissues. If it limited to a certain part of your vineyards, you may want to consider doing a spot treatment next year. Mancozeb, Zirum, captan, and phosphonate are effective materials, and QoI and SDHI materials are also effective too. Since none of them have kick-back activity against Phomopsis, nothing much we can do about the infection already happened; however, make sure to keep these materials in your tank mix so that you won’t suffer from Phomopsis fruit rot.
4) Luna Experience
As I mentioned back in February, Luna Tranqulity is no longer available for grape. Also, Luna Experience received a new supplemental label for a slightly higher rate of application (click here to download for your record keeping). Please keep in your mind that Luna Experience (and Pristine) has a 5-day REI for cane work (12 hours for all the other activities).
That’s it for today! Hopefully, we can enjoy better weather soon!