|I have several perennials and evergreens that are dying or dead from something turning it rust or tan brown. I've already used a pesticide spray twice now which seemed to slow it down. Just last Friday I put a systemic on shrubs and trees as a preventive and in the case of the miniature alberta spruce a last ditch effort to save it. It is over half brown and denuded of needles now.
|Although some diseases can spread to other plants, usually they are host-specific meaning they prefer a certain type of plant. If the problem is spreading throughout your garden it may be more weather related or indicate a water stress issue. A systemic takes months to work so if you recently applied it, you may not see results until this fall. The product needs to work its way through the vascular system and into all the tissues before it can affect insects that are feeding or diseases that are attacking. A rusty color on the leaves can indicate injury from insect feeding, a disease, sunscald, windburn, or even drought so until you can have the problem identified, I'm not sure what to suggest. Why not take a few specimens of the unhealthy leaves along with some of the healthy ones of each of your plants to your local cooperative extension office? Use a separate baggie for the leaves of each plant so they do not cross contaminate each other. Contact Texas A & M Cooperative Extension, 1102 Farm to Market 1294, Lubbock - (806) 746-6101. Helpful folks there can suggest control measures.