Mar 21, 2022
Dormant copper sprays and orchard sanitation urged in Mid-Atlantic

The spring temperatures felt across the Mid-Atlantic region are nudging the fruit trees to break their dormant slumber. Bud swell has been observed on our plum and peach trees in Biglerville, Pennsylvania.

The 2022 season is upon us, and disease management should kick into gear. In the words of Steppenwolf: Get your motor runnin’…

Dormant sprays to manage fungal and bacterial diseases

Growers are encouraged to apply dormant copper sprays on apples and pears for controlling fire blight and apple scab (and possibly other fungal diseases, such as apple blotch and bitter rot). When using copper, growers will want to aim for 2 lb/A of metallic copper: pay attention to the % metallic copper equivalent (and amount of metallic copper per unit) listed on the label of the copper you use. Also, late dormancy is the time to apply oil for controlling certain insects. During dormant sprays, it is okay to mix oil and copper. Since minimal green tissue is present, the risk of phytotoxicity from the copper-oil mix is very low. Consequently, emergence of green tissue will want to be monitored when this combination spray is used.

Since peach leaf curl can only be managed when leaves are off the trees, applications should be made prior to bud swell. Depending on your region, check your peach and nectarine trees for bud swell prior to any peach leaf curl spray right now. If bud swell has occurred, the window for peach leaf curl control has passed since the spores in the buds are no longer vulnerable to fungicides since they are protected due to the bud swell. If bud swell has not occurred, ziram, chlorothalonil (e.g. Bravo), and copper are peach leaf curl control options. Copper applications to manage bacterial spot are recommended.

Remove fruit mummies from peach and nectarine trees

While growers are finishing their winter pruning, it is very important to remove any mummified fruit hanging in the trees. This is especially critical for brown rot in stone fruit trees. Mummified fruit left hanging in the trees will become spore factories during the season and cause infection on blossoms and fruit. Fungicides can be overwhelmed with such high inoculum pressure. Consequently, sanitation is important for fruit rot prevention. In addition, be sure to remove any dead wood from your trees since this can also be a reservoir for brown rot spores.

Commercial fruit growers, please note:

When controlling for disease, weather and tree growth conditions need to be monitored at a local level within one’s own orchard. To assist with management decisions (especially infection events), growers can use the NEWA website, which has weather stations all over Pennsylvania. Before chemical products are applied, be sure to comply by obtaining the current usage regulations and examining the product label. Product information can be easily obtained from CDMS.

Kari A. Peter, Penn State University




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