What’s causing dried and curling leaves?

Have you ever seen anything like this in your garden?

A thoughtful customer from Minneapolis contacted us when she observed her plants dry and curl after using a fertilizer, treating with Plantskydd and applying an insecticide. She also asked why her Plantskydd had such a strong smell.

We asked gardening expert, Susan Martin for her advice. Here’s what she said:

“These plants are exhibiting classic symptoms of fertilizer and pesticide burn. This page from the University of Maryland Extension explains it well. Even though it is specifically about vegetables, the same principles apply to many kinds of plants. You’ll see the pictures there match what your customer is seeing on her plants: https://extension.umd.edu/hgic/topics/fertilizer-or-pesticide-burn-vegetables.

In my opinion, the damage shown in this customer’s pictures has nothing to do with Plantskydd. 

You have to be really careful how and when you apply fertilizer and pesticides/insecticides as they can easily burn plants. The bulletin explains this in detail, but generally, you should water your plants well before you apply any fertilizer and try not to spray anything on hot, humid afternoons. 

If the customer is finding that her liquid Plantskydd is extra-smelly, it’s because the product is too old and has gone “off”. Fresh product does not smell nearly as bad. I recommend that people dilute any leftover product with water and use it to fertilize their lawn, then start fresh with a new bottle of liquid Plantskydd when that happens. Oftentimes, people don’t use up the whole bottle in one season so they carry it over to the next, and that’s not a good idea with this organic product. It has a more limited shelf life than synthetic products. 

Gardener Sue’s News
Freelance horticultural marketer, writer, speaker and consultant based in West Michigan