An important disease of peaches and nectarines in Michigan is peach leaf curl. It is a fungal disease that can defoliate trees. Infected leaves and fruit become thick and crinkled with a puckered appearance. Affected areas often turn orange or red. Since primary infections take place under wet conditions in the late winter from bud swell to bud opening, now is the time to apply a treatment if you had a problem with this disease in the past. Autumn leaf curl sprays at or near leaf drop of Bravo or copper compounds such as Kocide, Tennacop, and COCS can be used now against leaf curl. Use sufficient water and proper sprayer calibration to insure uniform coverage.

In the spring with air temperatures between 50 to 70F, rain or dew moves the spores of this fungus into the swelling buds allowing the infection of young tissue. Prolonged cool wet periods during bud burst can result in severe infections. Effective spring controls include Bravo, Ziram, Ferbam (Carbamate) and copper compounds. Copper compounds have the benefit of providing some suppression of bacterial spot as well. Early spring applications at or before bud break are effective in controlling this disease. However, quite often growers miss this treatment timeframe in the spring and it is too late for copper sprays. Their buds have already started to swell. Once leaf tissue in the bud is infected, there is no effective fungicide treatment. Later fungicide applications can only reduce the severity of the disease. Again, now is the time to control peach leaf curl if you had this problem in the past.

That is all for today, this has been Al Gaus for Michigan State University Extension in Berrien County.