I don't think it matters much. The original Cornell formula is just ultrafine oil and baking soda in water, the soap is there to make it stick to the leaves and I believe the fish emulsion is just a foliar feed.

Thanks Lizzie!

I guess I can leave it out then!

Alexa

Liquid fish emulsion encourages the growth of beneficial microorganisms in the soil, but if you are worried about the odor attracting unwanted visitors to your garden you may want to use other things that have that effect on the soil, such as compost.

But -- don't skip the seaweed!

Liquid seaweed/kelp stimulates growth when applied to leaves or soil and I swear by it. I've been using Grow More brand cold-processed liquid seaweed with good effect -- Neptune's Harvest is another popular brand. Response is a more concentrated formula and it's an excellent product as well.

-- Janene

Would it be possible to get a copy of the cornell formula? Thanks. Chesh

This is the "recipe" and notes I saved from last year when Field posted it. Thanks Field!

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April through October, spray monthly (or only when needed) with the modified Cornell University organic spray (see formula below) to control black spot, powdery mildew, spider mites, and aphids.
Modified Cornell Formula: Mix into one gallon of water, in the order listed:
2 tbsp. of ultrafine horticultural oil (such as Sunspray oil)
1 heaping tbsp. of baking soda
1 tbsp. of fish oil/seaweed emulsion
3-5 drops of Superthrive®
1 tbsp. of mild dishwashing soap (such as Palmolive green -- but see note below)
.
[Note: Labels on newer containers of Sunspray oil indicate that it now contains an emulsifier. In that case, the dishwashing soap can be omitted.]
Mix well and spray with a pump-up sprayer late in the evening, after first watering your roses thoroughly and spraying them with the hose to scare off some, most, or all of the beneficial insects.
DON'T ADD VINEGAR. NEVER USE ANY TYPE OF FISH OIL/SEAWEED PRODUCT CONTAINING SULFUR WITH A HORTICULTURAL OIL SPRAY. AND NEVER MIX A CHLOROTHALONIL FUNGICIDE (e.g. Daconil or Fung-onilÂ) WITH HORTICULTURAL OIL OR USE THEM ON ANY PLANT WITHIN 10 DAYS OF EACH OTHER.
For black spot control, it is important that you spray all of the plant's wood, as well as the foliage. It has been found that the black spot spores reside in lesions in the canes and that they attack, not only the foliage, but also the canes and prickles.
Used with permission from the Field Report

Do I have to worry about spraying this in the sun?

Yes, you do. Water the roses well in the morning or the night before and then spray in the evening after the sun has set.

Hi. Maureen from Long Island here. Does this cornell formula really help the roses? How often do you have to spray, and what is a "pump up" sprayer? (I'm new to roses).

Also, can you buy the Cornell formula already made? or do I have to make my own?

Thank you,
Maureen