Perfectly ripe peaches are a gardener’s greatest reward when they mature in mid-summer. Peach trees (Prunus persica) are are small deciduous trees that grow in U.S. Department of Agriculture plant hardiness zones 5b through 8b, but are easiest to grow where summers are hot and dry. Summer rain and humidity foster numerous fungal diseases in peaches, requiring great diligence to prevent loss of the crop. Brown rot is one of the most serious, causing gummy infections on twigs and rotting the fruit before it has a chance to ripen. Chemical sprays are one of the main forms of control.
Watch for the swelling flower buds in late winter or early spring to be prepared for the spraying season, as brown rot may only be controlled if spraying begins before the blossoms open. Use fungicides containing captan, myclobutanil, cholothalonil or thiophonate methyl to treat brown rot on peaches.
Prepare for spraying when the flower buds turn pink on the outside, indicating that they are about to open. Mix the fungicide with water at the rate indicated on the label and fill the tank of the sprayer. Small handheld sprayers are suitable for a single tree and a larger backpack sprayer is preferable for spraying multiple trees at once.
Spray all the surfaces of the tree thoroughly, as well as the ground underneath the tree; the fungus that causes brown rot overwinters throughout the tree, especially inside the crevices of tree bark and on any debris on the ground. A good rule of thumb is to use one gallon of the fungicide solution for every 5 feet of tree height and width. For example, a tree 15 feet tall and 10 feet wide takes about 5 gallons to thoroughly cover the entire surface area.
Spray again every three weeks for complete control of brown rot as the fruit develops. The final spray should be about one week before harvest, just as the fruit reaches maximum coloration.
Things You Will Need
- Pump sprayer
- Rubber gloves
- Protective clothing
- Chemical mask
- The fungus that causes brown rot develops resistance to certain fungicides if they are used repeatedly. Alternate spraying different chemicals to avoid fostering resistant strains of the fungus. Sulfur is an all-natural fungicide that can be incorporated into the treatment regime, as well.
- Spray only when the wind is calm to make sure the chemicals end up on the peach tree rather than drifting to adjacent plants.
- Spraying peaches for brown rot needs to be accompanied by good sanitation practices to be most effective. Always rake up fallen leaves and fruit and prune off any dead or diseased wood. Dispose of these far from any other fruit trees.
- Wear rubber gloves, protective clothing and a chemical mask when spraying the fungicide. Avoid skin contact with the product and follow all instructions and warnings on the label.
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