2026 Disease Update: Dormant Copper Sprays and Orchard Sanitation

Punxsutawney Phil's 2026 proclamation proclaimed six more weeks of winter; however, it seems those six weeks will end abruptly the week of March 8. The current forecast includes high temperatures in the 70s and lows in the 50s for more than half the week. This warm-up may accelerate bud development, especially in early peach varieties. If you didn’t get a chance in the late fall to employ dormant fungicide and sanitation measures, there is still time to limit disease in their orchards this season.

Stone fruit

Stone fruit will most likely be most sensitive to this upcoming warm spell. If you did not apply your peach leaf curl sprays in late fall, it's recommended that you do so 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, monitor temperatures and bud development closely, and apply your fungicide as soon as possible. These forecasted warm days may be enough to encourage bud swell in early varieties, so late winter fungicide applications after the warm spell may be ineffective in controlling peach leaf curl because 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 preventing fruit rot. In addition, be sure to remove any dead wood from your trees, as it can also serve as a reservoir for brown rot spores.

Apples and pears

During the next several weeks, growers are encouraged to apply dormant copper sprays on apples and pears to control fire blight and apple scab, and possibly other fungal diseases, such as Marssonina (apple) blotch and bitter rot. When using copper, growers should aim for 2 lb/A of metallic copper; pay attention to the % metallic copper equivalent (and the amount of metallic copper per unit) listed on the label of the copper used. 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 need to be monitored when this combination spray is used, especially as we enter March with fluctuating temperatures.

There is still time to encourage the breakdown of remaining apples and leaves on the orchard floor. Consider applying urea directly to the ground, either before bud break or as late as green tip. Dissolve 40 pounds of feed-grade urea in 100 gallons of water (5% solution), spraying 100 gallons per orchard acre. Feed-grade urea is recommended for the ease of dissolving it in warm water, if available. If you choose not to use urea, be sure your nitrogen source is ammonium. This will help break down not only apples but also leaves that fell onto the orchard floor last season. When there are no sources of spores (e.g., old fruit or leaves), this significantly reduces the risk of early infection by these diseases. If fruit has been left hanging in the trees, there is no easy way to remove it. Leaving fruit to mummify is a risk for being a source of rot spores throughout the season. Removing fruit as best as possible is recommended to limit these future problems.

Additional Resources

Dr. Tree Fruit and Don Podcast

Penn State 2026 - 2027 Tree Fruit Production Guide

For 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 during infection events), growers can use the NEWA website, which has weather stations all over Pennsylvania. Before applying chemical products, be sure to comply with current use regulations and read the product label. Product information can easily be obtained from CDMS, Agrian, or Greenbook.