I posted this on ask a gardener also. The new growth on my zucchini plants is coming in yellow. Does anyone know why that might be?
Zucchini problem
When is the last time you fertilized? It may be too much or your plant has hit a hot spot with high nitrogen.
Before the picture was taken, I hadn't fertilized, other than the granulated fertilizer that is in the soil for a few weeks. I fertilized after because I thought the yellow indicated it needed it. I'm not sure if it helped or not. Here is a picture from today, next to the one from before. The other picture is of a plant in my neighbors yard on the other side of the fence. It looks like the same thing is happening to it. I think it's a weed.
There are a host of possibilities. Another is a deficiency which would be hard to diagnose without soil testing. Too much water can cause deficiencies in nutrient uptake when you would otherwise not have had a problem. If you have had a wet period this could be the problem especially in light of a similar problem nearby on a different plant. Weed and feed lawn fertilizers used nearby can also cause this look.
Thank you. We did have two weeks where it rained nearly everyday. I also know that my neighbor uses weed killer in her yard, but I think only spot treatments. I really hope they recover.