garden insect and disease products
When using one product for plant diseases (copper solution) and one for pickle worms and horn worms (Bt) how does one time the applications? Does one spray cancel out the other? I've used Neem oil in the past but find that fungal diseases and worms are not controlled. I would like to try the copper and the Bt but need help with the timing of the applications. Thank you for any assistance you can provide.
Certified GKH Gardening Expert
Using Bt effectively is absolutely timing-critical. The "worms" have to ingest the material as they feed on the foliage, and this is most effective in the early stage of the larval life cycle. As the caterpillars mature Bt will not be as effective; at later stages you would need to go with a contact spray for knock down. So knowing the pest life cycle and inspecting regularly for stage of life cycle is important. I would avoid other pesticide treatments during your Bt spray program. Bt spraying may be effective with one application, but it's better to follow up in a couple of weeks with a repeat spray.
You don't say what plants or what disease you are targeting with the copper spray. There are different copper fungcide products and some will burn green foliage. Copper fungicide is best used during winter dormant period, unless you are sure the product is one which is not "phyto-toxic".