pine beetles

Sap oozing from pine trunks can indicate an infestation of pine bark beetles.

QUESTION: With the summer heat, is it too late, and is it even worth trying, to put down grub control to get rid of moles?

ANSWER: It’s actually too early to put down grub control. Last year’s grubs became adult beetles in June and are now laying eggs for the next generation of grubs. Those young grubs will be feeding on grass roots in late August and through September. If you want to kill grubs, my advice is to apply the grub control in September. The grubs are young, and they are feeding constantly. If you actually have a grub problem, you’ll get good control at that time.

However, that may not be the ultimate solution. Moles tend to get even more active when they can’t find grubs to feed on. Therefore, you may see an immediate increase in mole activity after the grubs have been eliminated. Controlling grubs simply encourages the moles to look for food elsewhere. Of course, the sure-fire way to eliminate moles is with a steel kill trap.

QUESTION: I hope you can help me out by identifying what might be going on with some pine trees in my backyard. I have numerous pine trees, some are “clean”; some have a bit of sap seeping out of the trunk. On the worst tree, this sap excretion circles the tree, from the ground to 12 to 15 feet up the trunk. Do you know what’s happening?

ANSWER: Based on the photos you sent, this looks like the sap flow from damage done by pine bark beetles, or pine borers. These critters normally start in a tree weakened by something else. The adult lays eggs on the trunk, those eggs hatch into larvae that bore into the trunk and feed on the cambium, the growth layer under the bark. The holes they create allow for sap to run out onto the trunk, where it hardens and turns yellow or white. They can kill a tree by totally girdling the circumference of the trunk, restricting the flow of water and nutrients up and down the tree. They cannot live in a dead tree, so they frequently move to the next closest pine. You should definitely have these trees examined by a certified arborist. Addressing this as soon as possible can help save the trees that are not affected.

QUESTION: My mums are starting to get tall and spindly. They are in full sun, but I guess with all the rain in the early summer, they’ve just shot straight up. Is there anything I can do to thicken them up?

ANSWER: There sure is. You can clip off the last inch or 2 of each stem. Many gardeners do this monthly, from the middle of May until the middle of July. This practice is generally referred to as pinching them back. Left on their own, mums will frequently get too tall, too fast, and even start to bloom before the end of summer. Pinching them back forces the lateral buds to develop, giving you a nice thick canopy, and delays the blooms so you can enjoy their color in the fall.

QUESTION: I think my iris need to be divided. They didn’t bloom as well this year as normal, and the clumps are getting big. Can I do it now? Any tips?

ANSWER: This is an ideal time to divide them. I dig mine with a fork rather than a spade, being careful not to damage the bulbs. Clean all the soil off the roots, and use a sharp knife to make clean cuts as you separate the plants. Cut the fans back to about 2 inches tall, and plant them in their new location with just a shallow covering of soil. Planting them too deep or piling too much mulch over them will also reduce the blooms for next year.

Richard Nunnally is a freelance writer and is retired from Virginia Cooperative Extension. You can reach him at rtdgarden@gmail.com.

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