Am I killing my butternut squash with neem oil?

[Kieria]

I just transplanted these (I grew them from heirloom seeds) about 5 days ago into my raised garden bed and they were in perfect condition. Then I sprayed them with my homemade neem oil spray (made according to package directions) and then 2 days after they were sprayed they started looking like this. Not sure if it's a coincidence or if squash plants don't like neem oil? Couldn't find any information about that. I've tried looking up this problem, it looks like the leaves are almost burning in some places, there is white ALL over every single big leaf of all my butternut squash plants. There is no residue of any sort, so it makes me think it's not fungus, it's just getting these weird dried out/burned spots. And in this picture you can see right in the center it's starting to crack on the really dried out parts.The closest thing I could find was saying that it was from the squash beetle, but I cannot for the life of me find a single beetle or egg on any leaf or stem, and I scoured every single one. Any help or suggestions would be much appreciated!

[cynthia_h]

I have two questions whose answers may help solve this situation.

1) Where were the squash plants transplanted *from*? Were they in a sun-protected location? If so, were they hardened off before being put into full sun?

Plants can get sunburn.

2) What were you fighting with the neem oil? What critter(s) had you seen that needed neem? It's considered Major Artillery in the organic armamentum, something to be used when jets of water, soap spray, hand-picking, and other methods have proven to be ineffective or impractical. What was the enemy? Where, how many, how often, etc.?

Be aware that spraying neem is harmful to honeybees and other pollinators, so it's recommended to spray in late afternoon--dusk, if possible--so that the pollinators have "gone home" for the day. That way, the neem can work overnight on the bad guys and evaporate (volatilize, the components that are dangerous to bees) before the next morning.

If you could add your location to your profile, it will also help. The sun is of different strengths at different latitudes, from the Azores to Alberta. Because you're putting out squash plants in April, I'll assume you're in the Northern Hemisphere, but that still covers a lot of ground. Help?

Cynthia H.
Sunset Zone 17, USDA Zone 9

[rainbowgardener]

They do look kind of burned. I don't know if the Neem could do that. As cynthia noted, sunburn can look kind of like that, if the plants weren't well hardened off and used to the sun. Especially if the leaves were watered when it was sunny out, the drops of water on the leaves can act like little magnifying glasses creating bleached out spots/areas.

If it is sunburn, those leaves will never re-green, but the plant should not be affected and any new leaves that emerge will be fine.

[applestar]

I must admit I havent tried using neem oil yet, but most oil based sprays can cause burns when sprayed leaves are exposed to direct sunlight (think suntan oil). I think ones that are supposed to be safe generally have names like "ultra light" or "super light" horticultural oil spray. I don't know if neem fits in this category?

In any case, IMHO, almost all foliage spraying should be done on overcast days or near sunset. Only exception to near sunset is when using water only with no fungicide involved because then wet leaves overnight might invite fungal disease infection.

[Kieria]

Thank you for all the quick responses! Cynthia - Yes I had fully hardened off the plants a few weeks before and they had been spending 24/7 outside for some time before I transplanted them and were loving it outside. I'm in Florida (zone 8 ) and have had MAJOR problems with vine borers in the past and was hoping the neem oil would help prevent them from wiping out this years crop as they've done to every other squash plant I've ever had! I did spray them later in the day, but maybe it wasn't late enough and maybe I sprayed too much? I'm hoping that it's just a sunburn as everyone suggested, that would be best case scenario for sure... Thanks again applestar and rainbowgardener too, fingers crossed that's all it is