fall pest patrol: work now to foil deer, cabbage worms, viburnum beetle, squash bugs, voles
THE MOST IMPORTANT SUBSET of the fall garden cleanup chores: pest control. Fortunately all our needed cutbacks and raking of leaves–those sanitation efforts we’re all heading out to do, anyhow—help to reduce places for many garden pests to overwinter. But I go farther. I work to prevent a buildup next year of troubles like viburnum leaf beetle, squash bugs and borers and cabbage worms, and minimize damage by deer, mice and voles. The routine is the same in every case. What it comes down to: Eliminate habitat and hiding places, and eliminate some of the population. Pest by pest, some particulars:
I HOSTED A cabbage-worm field day here one recent year, apparently, and squished eggs and larvae like mad. Now I’ll be certain to clean up any cruciferous plants extra-carefully, to reduce the chance of overwintering pupae, and am reading up on weeds in the cabbage family (wild mustards, for instance, and shepherd’s purse, among others) with a sterner eye to their removal, too. Because kale and Brussels sprouts are so cold-hardy, and stand a long time into the winter garden for gradual harvesting (until Thanksgiving or longer), I have to be sure to pull the remains when they are done this year, even if it’s tempting to let some overwinter. The whole cabbage-worm story is here.
viburnum leaf beetle
SCOUTING FOR viburnum leaf beetle starts in late October here in Zone 5B, when leaves fall and their egg cases laid on this year’s viburnum growth are easier to see. Remove egg cases by pruning off affected wood, between now and April-ish, to reduce larvae and beetle issues in the coming year. The bump-like cases are usually on the underside of youngest twigs. I then also watch in May for larvae hatch (left) of any I missed, and rub the twigs then to squash the emerging pests.
I check every Viburnum, of which I have many species and varieties, but only a couple of cranberrybush types typically show any leaf damage, and now have egg cases. But why only those? Apparently there is natural resistance in many species, and you can get the list here if you wish to grow Viburnum but not ones that the beetle adores.
squash bugs and squash vine borers
THE KEY TO MANAGING squash bugs is to not let them build up—meaning vigilant egg removal in spring, and handpicking of adults, but also strict cleanup in the fall to reduce overwintering of unmated adults. The same is true of squash vine borers, which overwinter as larvae or pupae. Debris from all squash relative plants should be removed (some people burn it if there was a bad infestation). Best would have been to remove it right at harvest time, not just cutting the fruits and leaving the vines until garden cleanup later.
Other hiding places such as rocks, boards and such must also be moved aside. A rough turning of the soil may dislodge some pests, exposing them to predation by birds or other animals. All of this must be followed by prompt attention in spring, when young plants are especially susceptible and insect populations are rising. Growing a resistant variety, such as ‘Butternut,’ is helpful, especially if you had a recent problem. The full squash-bug story, and a thorough pdf factsheet from the the National Sustainable Agriculture Information Service provides more information on both of these pests of Cucurbits.
If you have issues with cucumber beetles, whose unmated adults also like to overwinter in plant debris and beneath other material on the ground, following the same sanitation practices can help.
KEEPING DEER OUT, or choosing plants that are somewhat less palatable for the areas where you cannot bar them, was the topic of a recent podcast. I’m not a big believer in “deer-proof” or even “deer-resistant” plantings as enough of a defense; I believe instead in fences, and my full rundown on creative ways to fence (some of which are not so ugly) is in the article on just saying no to deer with fencing. In fall, before any snow flies, it’s critical to check the fenceline for any breaches (something I do regularly), and also for any overhanging limbs that might better be pruned now rather than risk having them fall in winter, damaging my deer barrier.
mice and voles
CLOSE-CUTTING THE entire lawn, with special care to clear weeds and turf around the trunks of woody plants, is just one step in this heroic battle against these small but voracious rodents. Mice are also an important link in the Lyme Disease chain, so I have zero tolerance of them getting indoors. Installing hardware-cloth or plastic tree guards is another—and so is trapping, which I accelerate my efforts at starting in late August. I have some tricks—including an idea for a box built to enclose mousetraps that I borrowed from sustainable agriculture expert Eliot Coleman—all of that is covered in this article.
Critical point: You must never use highly toxic mothballs for rodent control or any other unregistered application.
A note on a larger mammal, the rabbit (who I am reminded is a lagomorph, not a rodent): They’ll browse woody plants in winter, too, and relentlessly. As with deer, I think they are best controlled by fencing, using 48-inch-high mesh no larger than an inch diameter, burying it about a foot with the rest above ground, supported with stakes or posts.
An aside on moles (who are not rodents but insectivores): They can be frustrating with all their tunneling, yes, but they aerate the soil and eat grubs, so I generally celebrate their activity (well, after cursing every now and again when they uproot some lovely thing in the process of hunting food). I have long believed that reducing grubs (such as those of Japanese beetle) In the turf and beds would reduce their food source and therefore discourage the moles, but various experts including Purdue say this is not true, because earthworms are their primary food.
Are there pests you’re working to get ahead of for next year now?