Grow a peach tree in your yard and you’ll never go back to store-bought fruit: dreams of sweet, sticky juice running down your arm as you suck the tender flesh from the pit will keep summer alive even through the worst of winters. That is, unless you ignore the warning signs of common peach diseases and your poor tree succumbs to one of them.
Peach tree diseases and fungus aren’t uncommon and they can affect nearly any part of the tree. The types of peach tree diseases can be divided in groups by the causal organism, although the vast majority of common peach diseases are caused by some variety of fungus working against the tree. Peach disease control relies on the gardener to recognize symptoms early and treating peach disease as swiftly as possible.
Common Peach Diseases
Below are some of the most common types of peach tree diseases:
Bacterial spot attacks fruits and leaves, causing purple-red spots with white centers to appear on leaf surfaces that may fall out, leaving a shot-hole appearance. Bacterial spot on fruits starts with small dark spots on the skin, gradually spreading and sinking deeper into the flesh.
Fortunately, damage on fruits can be cut out and the fruit still eaten, but marketability suffers. Good cultural care is critical for preventing bacterial spot. A few partially resistant peach varieties are available, including Candor, Norman, Winblo and Southern Pearl.
Brown rot is arguably the most serious disease of peach fruits. This fungus can also destroy flower blossoms and shoots, beginning at bloom time. Small, gummy cankers appear on infested tissues, spreading to healthy green fruits when wet weather sets in. Infected fruit develop a small, brown spot that expands to include the whole fruit. Eventually the fruit will mummify on the tree.
Remove all mummies from the tree to break the life cycle and apply a fungicide with thiophate methyl, captan or azoxystrobin just before fruits begin to ripen.
Peach Leaf Curl
Peach leaf curl appears some springs, causing thick, puckered or distorted leaves with a red-purple cast to develop in place of healthy leaves. Affected leaves eventually grow a mat of gray spores, dry out and drop, weakening trees. Once this first round of leaves has dropped, few to no signs of peach leaf curl will be seen the rest of the season.
A single spray of lime sulfur or copper fungicide all over the tree each winter should prevent future problems.
Peach scab, like bacterial spot, primarily manifests as aesthetic defects on fruits. Small, dark spots and cracks appear on the surface, but may be so numerous they grow together into large patches. Shoots and twigs may develop oval lesions with brown centers and raised purple margins.
Increasing the air circulation in the canopy by pruning the tree severely may help, as will the use of a protectant fungicide such as wettable sulfur, azoxystrobin or captan. Spray the tree five times at seven to 14 day intervals after petal fall.
Peach yellows is a common problem in trees that aren’t already on a spray program and is vectored by leafhoppers. Leaves and shoots may emerge deformed into witches brooms, while fruits ripen prematurely, with a bitter taste and poor fruit quality.
All or just part of the tree may be affected. Unfortunately, there’s no cure for peach yellows – once symptoms are obvious, removal of the tree is the only option.