Disease News

Fruit Crops: Dormant and Bloom Sprays

Fire Blight. Fire blight is the most important disease of apples in Illinois. It occurs every year and cause blossom blight, shoot blight canker blight, and rootstock blight on apples and pears. To minimize the losses to fire blight dormant copper spray and application of antibiotic during bloom is recommended. Copper must be sprayed prior to or at silver tip growth state. Copper should be applied to the entire orchard block, including non-susceptible cultivars. The reason for treating non-susceptible cultivars is that even normally fire blight resistant trees can be colonized by the bacteria and serve as a source of infection during bloom. Several copper compounds can be used in the dormant sprays. If copper sulfate is used, it must be applied when trees are dormant. If copper sulfate is later than silver tip, plant injury can result. Also, do not apply copper sulfate with oil; apply copper sulfate and dormant oil as separate sprays spaced at least 10 days apart. Fixed coppers such as Kocide and C-O-C-S can be tank mixed with early season oil sprays. For more information, consult the "Illinois Commercial Tree Fruit Spray Guide 2002." Also, a detail information on fire blight can be found at the website.

Peach Leaf Curl. In 2002, some unprecedented peach leaf curl incidence observed in Illinois. To control leaf curl, peach and nectarine trees should be sprayed during dormant season. Trees can be sprayed after leaves drop in the fall or before buds swell in spring. Chlorothalonil, carbamate, ziram, or copper compounds can be used for dormant spray to control peach leaf curl. For more information, consult the "Illinois Commercial Tree Fruit Spray Guide 2002." Also, more information on peach leaf curl is available at website.