The Pacific Northwest includes the states of Washington, Oregon, Idaho, Montana and Wyoming. This collection of territories also includes the Canadian province of British Columbia. The land throughout provides an array of growing conditions, from dry desert soils to nutrient-rich loams. Although the soil conditions may vary, the native plants of the Pacific Northwest share many common diseases.
Powdery mildew is a fungal disease caused by an array of fungal species. This foliage disease infects a wide collection of plants, as well as trees, throughout the Pacific Northwest. Transported by fungal spores, powdery mildew infects the young, developing foliage during the early spring periods. Although mature leaves are susceptible to powdery mildew infections, they are less susceptible than young foliage. The infected foliage develops powdery white fungal coverings across the surface of the leaves that conceal coalesced and necrotic fungal spots. This fungal disease favors damp conditions with poor air circulation and high humidity levels. Powdery mildew can be controlled with fungal spray treatments and pruning of the infected areas.
Botrytis blight, or early blight, is a rotting disease. This fungal disease, transported by fungal spores, matures at the base of shoots and blooms as they develop in the early spring. Before the development is complete, the shoots and blooms experience sudden wilt and death, and take on a wilted or drooping appearance. Botrytis blight infections are accompanied by the appearance of gray mold which develops over the rotting, infected areas. Infected bud and flowers rot and stems turn brown. The plant takes on a scorched appearance and often experiences premature defoliation. Botrytis blight thrives in defoliated debris and favors the damp, rainy spring season. The disease can be controlled with a combination of pruning, chemical control and debris removal from around the plant. Good air circulation is also essential in reducing potential botrytis blight infections.
Fusarium wilt is a soil-borne fungal disease that is especially damaging to its hosts. This indiscriminate disease infects plants through the root system and causes the destruction of the plant’s vascular system. Infected plants experience, in essence, a progressive starvation because the vascular system becomes unable to transport ample amounts of water and nutrients throughout the plant. Externally, the infected plant will experience foliage discoloration, droop, dieback, heavy defoliation and growth stunt. Internally, the vascular system will take on a blackened and wilted appearance. There is no cure or treatment for fusarium wilt.