Does a loss of leaves cause grapes to drop?

General Fruit Growing
#1

I recently had about half of my grapes fall off the vine. This going sided with massive leaf damage from caterpillars in Beatles. Did the loss of leaves mean the vine couldn’t support the fruit and automatically dropped it?

#2

I’ve never seen fruit drop on grapes other than that right after pollination. When I’ve had leaf loss from hail the fruit hangs on. That’s not just grapes but everything.

#3

Yes, loosing leaves can cause fruit to drop. The leaves photosynthesize producing the carbohydrates that go into the fruit. But the rest of the plant needs carbohydrates for food just as we do. If there is not enough carbohydrate production to supply the needs of the plant and fruit production, most plants will drop the fruit. They are hardwired to prioritize survival and having enough energy to break dormancy and undergo a growth spirt the following spring.

There are a few grape varieties where selective breeding has resulted in the plant prioritizing fruit production. The muscadine that is famous for doing this is supreme. Supreme has a tendency to overtax its leaves, then drop the leaves and not drop the fruit. The fruit never really ripens properly and the plant doesn’t have energy to break dormancy the next spring and dies. This is not a good characteristic. Dropping fruit after leaf loss is an important self defense mechanism. God bless.
Marcus

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#4

Alright that makes sense. So I must attack the beatles and these catapillar that eat the leaves if I want grapes. Are they likely the species?

#5

If you want fruit, you have to have leaves and lots of them. Anything that eats the leaves are eating the factories that make the sugar that go into the fruit. Attack any insect that attacks any part of the plant. Malathion will get most things and is relatively safe as far as insecticides go. Follow the directions and try to keep it off of you. It’s not intended for enclosed spaces like inside a house. But once applied, it dissipates pretty quickly. God bless.

Marcus

#6

The directions on the bottle of pesticide will tell you how many days you have to wait after application before you can safely eat the grapes. Note, always wash fruit before eating if you have ever applied any pesticide while that piece of fruit was on the plant. God bless.

Marcus

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#7

Ok, Ill try to find something.