bugs

[trevor]

I grow Chardonnay.
In April I spray against oidium.
Then, every 2 weeks, from May to August I pray with systemic and contact fungicide against perenospera (changing the chemicals every month)
In June I add a foliar feed.
In July/August I include a spray against oidium.
I try to keep the canopy open and remove a lot of leaves in August.

Every year, I get perenospera and oidium.

Please ... what am I doing wrong ?!

 

[blumentopferde]

I find it a bit strange that you start to spray against oidium so late. I include the sprays against oidium from the beginning of the growing season...

Apart from that: How do you recognize that you have Peronospora and Oidium? I ask because once I thought I had all kinds of funghal diseases but in the end it came out that I damaged the leaves with my spraying...

 

[trevor]

Thanks for your reply.

Oidium spraying. Ah ... so I should start that much earlier (assuming we don't still have snow in March!). At the moment, I spray the trunk of the vine as well as the spurs after I have cut off last year's growth and have tied in the new shoots.

Perenospera shows itself as white patches under the leaf (usually with corresponding brown patch on the top of the leaf). It spreads to other leaves very quickly.
Oidium starts as a grey kind-of-powdery look on the grapes (which could be anything really). This then develops into dark blotches, which get bigger and spread to other grapes in the bunch. Spraying with Karathane makes these damaged grapes shrivel up and die.

 

[blumentopferde]

Thanks for your reply.

Oidium spraying. Ah ... so I should start that much earlier (assuming we don't still have snow in March!). At the moment, I spray the trunk of the vine as well as the spurs after I have cut off last year's growth and have tied in the new shoots.

Perenospera shows itself as white patches under the leaf (usually with corresponding brown patch on the top of the leaf). It spreads to other leaves very quickly.
Oidium starts as a grey kind-of-powdery look on the grapes (which could be anything really). This then develops into dark blotches, which get bigger and spread to other grapes in the bunch. Spraying with Karathane makes these damaged grapes shrivel up and die.

Sorry I overread that you spray in April!

What I find strange, is that you don't spray against Oidium between May and August. Or do actually spray against Oidium and I misinterpreted your posting?

You seem to use potent sprays, I can't think of anything else you could do but shortening the spraying interval....

 

[trevor]

Thanks for your thoughts.
I see July as the danger time because it can be very hot but we also have violent storms. Hot and wet is not good, so I 'hit everything' at that time of year.
Chemicals ... I can see no point in being 'polite', so I go for these bugs with the best that I know of !
As you suggest, I will work on shorter spraying times. Perhaps every 10 days instead of every 14 will do the trick.