A few weeks ago, we questioned Punxsutawney Phil’s proclamation about an early spring when we had two snow storms in the middle of February. However, perhaps Phil’s early spring prediction was accurate with the unseasonable temperatures lately. Although it feels like the 2023 season finished yesterday, the 2024 season is upon us. There are measures growers can employ in March to limit disease in their orchards this season. Dormant sprays to control fungal and bacterial diseases should be considered soon. In addition, managing leftover fruit in the trees and on the orchard floor is also discussed.
Stone Fruit
If you did not apply your peach leaf curl sprays in the late fall, it’s recommended that this be completed as soon as possible. Peach leaf curl spores are exposed when the leaves are no longer on the trees. This is your only time to manage the disease. If you have waited until late dormancy to apply the fungicide, closely monitor temperatures and bud development. These warm days may have been enough to encourage bud swell in early varieties, such that late winter fungicide applications may be ineffective in successfully controlling peach leaf curl because the swollen buds will protect the spores. The following fungicides can be used: copper, ziram, lime sulfur, or chlorothalonil.
While growers finish their winter pruning, removing any mummified fruit hanging in the trees is very important. 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 of 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.
Apples and Pears
Growers are encouraged to apply dormant copper sprays on apples and pears to control fire blight, apple scab, and possibly other fungal diseases, such as apple (Marssonina) 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 to control 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, the emergence of green tissue will want to be monitored when this combination spray is used, especially with the current fluctuating temperatures as we enter March.
Another issue following us from the fall is the large amount of fruit abandoned in the orchard after the 2023 season. This issue can be an excellent fungal spore source for fruit rots and other problems to wreak havoc in the orchard this spring.
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Photo Credit: minnesota-corn-growers-association
Categories: Pennsylvania, Crops