Black Rot

[BobR]

We have had so much rain here in central Illinois that black rot has already taken over. Saw my first Japanese beetle today, but with rain and thunder storms in the forecast for the next seven days, it won't do any good to spray. I think this is worse than last year.

 

[grapeman]

I feel your pain with the rain Bob. It has become a nuisance here also. The season came in dry and has turned wet over the last three weeks. Whet you are showing in the picture lokks more like anthracnose than black rot. Notice the round brown spots on the grapes with a darker center making it look like an eyeball or target? That indicates anthracnose. Blakrot is more irregular in shape on the fruit. On the leaf and shoots you get lesions with a sunken area on the shoots. Black rot has light brown spots on the top of the leaves with a circle of darker spots near the outside of the spot. Fortunately most black rot sprays also take care of anthracnose. Check your label and see if it covers anthracnose in grapes.

 

[BobR]

Thanks, I will do that Rich.

 

[djrockinsteve]

Start a spray program to eliminate black rot. We have lost entire crop for two years until understanding what it was and treatments. Finally I believe it's under control.

I use a variety of chemicals and spraying times to stop it. Black rot comes from within the plant. Once it's spotted it's usually too late.

Good luck.

 

[grapeman]

Black rot doesn't come from within the plant. It can overwinter in grape mummies and sometimes on canes and grows there. Those release spores which land on either the leaves or the fruit and it grows from there. It will develop little brown spots on the leaves and you can see a little black spots called pycnidia within it if you look closely. Yes you need a spray program to prevent black rot and also the anthracnose bob has. Here is a pdf file with pictures showing black rot
http://nysipm.cornell.edu/factsheets/grapes/diseases/grape_br.pdf

 

[davidfilip]

Yeah, they like to overwinter on canes or in the soil nearby and spores will land on leaves and new grape clusters. I find crucial to do one or two sprays before flowering, I also remove quite some leaves to keep good ventilation inside the plant.

 

[dwhill40]

Hello,

After three weeks of daily rains prior to bloom I can tell you without doubt, with black rot the orange-ish dots on the leaves will be obvious.

The vines were infested even though my vines and floor were spotless, I didn't spray lime and sulfur prior to budding like I should have.

I sprayed with mancozeb prior to bloom and then had three weeks of no rain and not a single tag of grapes have the black rot. I've sprayed every two weeks since with the immunox product. Things seem to be under control.