How does it work?

THE OAK WILT DISEASE: All oak species native to North America are susceptible to oak wilt. The White oaks are somewhat resistant to the oak wilt fungus. Red oaks and the live oak are highly susceptible and this includes the lacey oak, in spite of it being of the white oak family.

The beetles fly to healthy oaks and feeds in the small twigs crotches and upper branches. The water conducting vessels (the xylem) are exposed to the beetle-carried spores as the insect feeds through the bark. Once established, the fungus can move through the tree’s vascular and phloem systems, resulting in systemic infection. The initial fungus spread is relative slow and the developing infections are not apparent until the fungus moves into the larger branches and then rapid wilting will occur. The disease is also spread from the same species by interconnected root grafts. Death of a tree infected through root graft is much more rapid than caused by the beetle.

A Sterol Biosynthesis Inhibitor

The triazole fungicide Propiconazole is effective in management of the oak wilt disease, it possesses systemic and some curative properties against certain fungal diseases. It is a highly systemic sterol inhibitor that penetrates and trans-locates, preventing fungal cell development, by interfering with cell wall formation and growth throughout the plant by inhibiting sterol biosynthesis.

Propiconazole has protective, curative and eradicant activity, although best results will be achieved when it is applied when the disease is still in the early stages of development. It is recommended that application begins when conditions are favorable for disease infection and at the very beginning of disease symptom expression.

Propoiconazole is absorbed into the fungus where its two modes of action attack fungal cells at several sites altering the cell, thereby inhibiting sulfur-containing enzymes and disrupting fungal energy production. It has preventive activity, and is primarily active on mycelium with some anti-sporulant activity, and prevents spore germination. . The commercially available formulation of propiconazole 14.3% MEC (microencapsulated) is available but not limited to; KESTREL®, Quali-Pro ®, and Alamo ®,.

Propiconazole at the highest label rate (therapeutic treatment of 20 mils per diameter inch) may provide protection for multiple seasons. However there is no residual activity in the tree after 23-24 months. The preventive dosage rate is 10 mils per diameter inch for trees up to 20 inches in diameter and for trees greater than 20 inches diameter due to their value and size, the 20 mil dosage per diameter inch is highly recommended Foliar toxicity of propiconazole is low, even at rates of up to the highest label rate, though severe phytotoxicity may occur with high dosage rates on small diameter trees when treated early in the growing season. Propiconazole does not require high dilution rates with water so treatment is considerably faster uptake, and there is less tissue injury at the injection site due to the fact that it has a near neutral pH.