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.

I hadn't heard of Neem meal until your post, so I looked it up. Apparently, Neem Seed Meal is what's left of the seed after the extraction of oil. Therefore, it shouldn't burn like the Neem oil does. Down to Earth says the meal "is an excellent way to strengthen root systems, improve plant immunity and balance nutrient levels in the soil". According to reviews, the downside is cost compared to other seed meals and an unpleasant Neem smell. But perhaps the benefits are great. I hope you report back on how it does for you. I'm especially interested if you think it helps with insect resistance. I might give it a try.

Neem has some fungicidal properties but how those may be activated when used as soil drench for roots is unclear. And to clarify, neem can be used as a systemic drench. It is effectively drawn up by the plant tissue and can deter insect pests but is not that long lasting and will need to be reapplied for maximum results. " Firstly, when used as a soil drench, neem oil acts as a systemic insecticide. The oil is drawn up into the plant's vascular system by the roots. This means that its present throughout the plant's structure, and harmful insects that feed on your plant will be exposed to it. ".

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.