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Can fungus in tree stump harm nearby plants?

A many-zoned polypore (Coriolus versicolor) fungus on a

A many-zoned polypore (Coriolus versicolor) fungus on a tree on reader K. Fitzpatrick's Mastic Beach property.

DEAR JESSICA: A tree in my yard was cut down about four years ago, but because there is a big piece of metal in the stump, it could not be ground. Last year, it started getting scale-like stuff on it, and it's eating away the stump, which is OK because I want the stump gone. I'm assuming it's some sort of fungus. Do you happen to know what it might be? Can it hurt other trees on the property? The trunk is a foot away from my garden boxes. The most important question is can this affect my garden vegetables and, in turn, affect my family? -- K. Fitzpatrick, Mastic Beach

DEAR K.: What you're seeing is a many-zoned polypore (Coriolus versicolor), a common bracket fungus adorned with colored rings that grows stacked in large groups, as your photo depicts. This group of fungus thrives on dead wood, such as your tree stump, and expedites decay.

It's interesting to note that, although it is not considered edible, this mushroom is used in traditional Chinese medicine, and has slowed the growth of cancer cells in some studies, according to the American Cancer Society.

As far as posing a threat to the surrounding trees and plants on your property, the answer to your question is yes and no.

"C. versicolor on an old stump would not be a threat to adjacent trees unless those trees had gaping injuries," Marc Dilley, an apple breeding horticulture specialist in Washington state who has studied the fungus, told me. Spores can certainly become airborne, but only trees already weakened by drought, low nitrogen or damage would be at risk, he said.

Your vegetables are safe, but remember that other fungi and bacteria will take hold in the right conditions, such as when plants are overwatered.


DEAR JESSICA:I have a peach tree that I purchased from Lowe's and wanted to know how to tackle pruning and address insects that seem to be attracted to the tree. -- Lou Caliguri, Smithtown

DEAR LOU: Peach trees thrive best when the soil's pH is between 6.5 and 7.0. I recommend testing your soil and making amendments as necessary to achieve that range. Test kits are available at most nurseries. To ensure adequate nutrition, fertilize trees with a 5-10-5 or 10-10-10 product annually in early spring.

Peaches produce fruit on year-old wood (the prior year's growth). To ensure vigorous new growth, prune back hard every year when the tree is in flower. This timing will allow you to see how your cuts will affect the current year's crop. In late spring of the second year, cut back the central leader to just above the first wide-angled branch. Select three to five scaffold limbs that give the tree a vaselike shape and remove the others.

Keeping the ground around your tree free of fallen leaves, fruit and other debris will help reduce pest problems. Weeds, for instance, harbor stink bugs, which eat holes in fruit. Plum curculio beetles lay eggs in hanging fruit, and their offspring burrow into the ground, where fallen fruit would offer protection. Peaches also are susceptible to aphids, leafrollers and mites. Ladybugs, which usually can be purchased only early in the season (online or at larger nurseries) feed on all of those.

In addition, planting Queen Anne's lace or yarrow under trees will encourage the beneficial predators to stick around. Preventive neem oil sprays also are safe and effective.

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