Ive called my local university co-op extention on this as it doesnt seem as if anything that will supress something as small as mold and spores, would easily be killed by an oil application. The catapillars need to eat to have bts and other bacterias, g if the get hit by oil that may very well kill them or cut back. The bt breaksdown quickly in sunlight. So it is better to spray that first a day or two before oils at evening giving the little boogars time to injest it. Bt takes time to act within. It takes about 2-3 days to kill. In the next spray if you must spray oils then spray then. Or you can find a biological "pre-emergent" (pe) there are organic ones. A few days after that up to 7 days release beneficial insects such as wasps, pirate bugs, mealy bug destrpyers, what ever pest you need to control. There are many. Disease is now the biggest threat & there are beneficial sprays just for disease.. oils work ok but there are a few beneifial baterias that kill and supress. Unfortunately, you have to spray more than once but with this prescription you wont need to spray as often. Ive only sprayed once since june, i live in a coastal area lots of fog and wet. Now today i have to spray...two months between sprays darn well worth the cost and time.

We were at 8 weeks on our black bean plants beautifully making their way up the trellis, when we decided to treat the leaves with Neem oil spray. A number of holes had appeared in the leaves which we presumed to be the result of aphids. We applied the Neem spray at 6pm. Instructions on the bottle asked the user to spray so that leave was saturated, and that to be effective, entire plants needed to be sprayed. The following days, the lower leaves turned yellow and began falling off. Tested soil: pH of 7.8 (slightly alkaline), and moisture meter (which shows indications of dry, moist, and wet) has the needle pointing halfway between moist and wet. I'm thinking that the runoff of the neem oil in the soil causes inability of root system to take up iron, or nitrogen, or both. Going to add 2 teaspoons of vinegar to gallon of water for next watering, and going to spread coffee grounds to add some nitrogen to soil. Any other ideas would be greatly appreciated as it is disappointing to see the plants suffer this late in the season.

This from Beyond Pesticides (formerly National Coalition Against the Misuse of Pesticides) ...Neem oil: Neem oil is extracted from the tropical neem tree, Azadirachta indica, contains insecticidal properties that are composed of a complex mixture of biologically active compounds. It has a strong, slightly garlic-like odor that some people describe as unpleasant. Its various active ingredients act as repellents, feeding inhibitors, egg laying deterrents, growth retardants, sterilants and direct toxins. Neem has both contact and systemic action in plants. The active ingredients biodegrade rapidly in sunlight and within a few weeks in the soil. Neem oil has very low toxicity to mammals. Clarified hydrophobic extracts of neem oil are used to control some fungal diseases of plants. In India, neem products have been used in toothpaste, pharmaceuticals, and as a grain protectant for centuries without apparent harm to humans. I can't remember which, but some US corp has patented neem oil specifically because of its low toxicity.

It looks like you have a case of root mealybugs. I have a similiar problem and I don't know exactly how many plants are affected so I may have to use some serious chemicals. In your case if you only have a small number you can unpot them, spray off all the soil and bugs with a strong hose sprayer and then soak the plant in water heated to 120 F. I would then let the plants rest in a shaded area or the garage for a few days to let any damage to the roots scab over before replanting. Use a temperature gauge to be sure the water isn't too hot. Dispose of the infected soil. Try to avoid putting plants back in areas where they could be reinfected from infected plants. I had placed a number of potted succulents togerther in a large saucer and all the plants were infected by mealybugs traveling freely in the saucer. I just read that plants housed in greenhouses with wire benches have much less problem with mealybugs. Unfortunately I just finished building new wood benches! Good luck and I hope you can save your plants.