|I have noticed green grasshoppers on my roses. I suspect they may be attacking other plants as well. Is there anything I can do other than putting a screen over the plant? I have many rose bushes. Why do they come back if you use an insecticide? Any new things on the market or new suggestions? I have blight (white fungus) on rose bushes, I try to keep it under control. I water from the below|
|Grasshoppers are difficult to deter because they come in from neighboring fields and yards. A biological control disease organism, the protozoan Nosema locustae might work. Nosema locustae is most effective on young grasshoppers. This biological control will reduce grasshopper numbers over a few days or weeks, but, generally, it is a slow-acting disease that takes at least a year to affect grasshopper populations. N. locustae is available at many garden shops and nurseries and is sold under various trade names. Use this product strictly according to label instructions. Because adult grasshoppers are older and tougher than the nymphs, they are more difficult to control. Deter them from your garden by keeping other areas of your property well-watered to provide a lush alternative to your garden.
The white fungus on your roses is probably powdery mildew. Powdery mildew fungi spread quickest when the humidity is high and temperatures are between 50F and 90F. To discourage the disease, plant on sites with good air circulation, give the plants plenty of space, water during the morning only, and allow the soil to dry out between waterings. Remove any affected leaves as soon as you see signs of the disease. For heavy infestations of powdery mildew, sulfur or copper sprays can be applied weekly, starting in June in your area. These include: sulfur, neem oil (Rose Defense, Shield-All, Triact), triforine (Ortho Funginex), or potassium bicarbonate (Kaligreen, First Step) Chemicals are most effective when combined with cultural controls. Best wishes with your landscape!