Organic pesticides are usually considered as those pesticides that come from natural sources. They are usually minimally processed. These natural sources are usually plants or minerals. There are also microbial pesticides.
Excessive summer irrigation of oak and madrone trees may promote fungal diseases such as the oak root fungus (aka armillaria root disease) and crown rot.
This article briefly discusses the most prevalent madrone disease problems, then offers a broader perspective on the health of this southern Oregon native.