I've used liquid kelp as a foliar feed in my veg garden, and I've planned to make some aerated compost tea as a foliar feed but haven't gotten around to it.

When it gets in the 90s around here (rarely), it helps to spray plants with water in middle of the day to cool them down, otherwise they can burn in the unaccustomed heat -- have seen hydrangea leaves curl up and turn brown on a hot day.

The rose buyer at a local nursery recommends Maxsea 16-16-16 solution (1 tbsp to 1 gal water) as a foliar feed every 7-14 days. (She also uses Dr. Earth Rose and Flower Fertilizer with Mycorrhizae to feed the soil and roots.) She says this has eliminated serious mildew problems her roses had had before.

She also recommends an early-morning spray of water on roses, which she says discourages aphids and spider mites and reduces or eliminates the need for fungicides and pesticides in her garden.

Here is a link that might be useful: Yamagami's Nursery

Thanks, Habitat, for answering my post. I am not familiar with the products you mentioned because we live in a different area of the country, I presume. I will look into this. I always hesitate to spray water on the leaves because of the blackspot, but I don't believe a spray of water will do any more damage than what has already been done. I have looked for the kelp or seaweed, but have not been able to find it here. Thanks again - Barb

Water on the leaves is good if it will dry in less than eight hours, but bad on humid evenings where it may stay all night and germinate black spot spores.

If it is extremely hot (overnight low around 80), fungus diseases don't spread readily, so you can spray less or not at all. However, Cornell mixture could probably be used in the morning if the soil holds plenty of water.

When you spray is determined by what you are spraying for, although a general rule of thumb is to never spray during the heat of the day, roughly after 9:00am or before 6:00pm.
What would you want to spray the Cornell formula for?

Kimmsr - I understood that the Cornell spray would help with the blackspot. We are having such swings in temperatures and extremely hot weather--little rain, that I thought I needed something to help. They are looking pretty sick - Barb