Fusarium Wilt

Marijuana Horticulture

by Jorge Cervantes

Identify

Fusarium wilt is most common in warm grow rooms and greenhouses. Recirculating nutrient solutions above 75F creates perfect conditions for Fusarium. The water and nutrient solution carries this disease with it when contaminated. Fusarium starts as small spots on older, lower leaves. Interveinal leaf chlorosis appears swiftly. Leaf tips may curl before wilting and suddenly drying to a crisp. Portions of the plant or the entire plant will wilt. The entire process happens so fast that yellow, dead leaves dangle from branches. This disease starts in the plant’s xylem, the base of the fluid transport system. Plants wilt when fungi plug the fluid flow in plant tissue. Cut one of the main stems in two, and look for the telltale reddish-brown color.

Control

Use fresh, clean growing medium. Avoid nitrogen overfertilization. Preventive action is necessary. Keep nutrient solution below 75F. Hydrogen peroxide infusions will also arrest Fusarium. Always remove infested plants and destroy.

Biological

Mycostop, or Deny, or Dagger and Trichoderma.

Sprays

Treat seeds with chemical fungicides to eradicate the seed-borne infection. Chemical fungicides are not effective on foliage.