Oct 1, 2023: Fall pests & diseases, planting garlic, strawberries; pest talk open to all

From Linda Gilkeson:

Well, that seemed like a rather quick transition from summer to fall last month! Here are a couple of pest and disease issues and planting notes that are top of mind for this month:

Insect barriers: A common question is when it is safe to remove insect netting from beds of carrots and cabbage family plants. With the long, warm summer we just had, it is likely that adults from a large third generation of carrot rust fly and cabbage root maggot are still around, laying eggs on warmer evenings–so don’t take a chance on uncovering beds too early. It is best to keep plants covered until end of October or after the first hard frost, whichever comes first.

Powdery Mildews: The usual late summer dusting of fine, whitish powdery mildew spores have been appearing on leaves. Different species of PM fungi infect different host plants so just because it show on one kind of plant doesn’t mean it will spread to unrelated plants. The most common PM species infects squash leaves, peas and various ornamentals; in some years there are PM species that infect Swiss chard or kale and other leafy greens in the mustard family. More rarely, tomato plants have powdery mildew. The onset of wetter weather this month will slow the spread and, eventually, rainy weather stops PM infections as the leaves become too wet for the spores to germinate. There is no need to cut off infected squash leaves as that won’t really help to control the disease. Just compost infected leaves and plants at the end of the season and plant squash in a different bed next year. There is also no need to discard kale or other hardy vegetable plants that have PM on their leaves now. New leaves that will develop during fall rains and that grow next spring won’t be infected.

Garlic: If your harvested garlic had grey, mouldy areas around the neck or root end of the bulbs or if the peeled cloves show, pinkish-orange lesions, those are signs of various root rots. These rots continue to spread during storage so rather than lose the crop, you can salvage any intact cloves by peeling and freezing them (no blanching necessary). Get a new supply of healthy garlic to plant in October for next year’s crop and be sure to plant them in soil that hasn’t been used to grow garlic, onions or other related plants for at least 4 years. Most garlic root rots can be prevented by rotating crops and ensuring only healthy cloves are used for planting. The one symptom that is rarely serious comes from a fungus called Embellisia. Tiny spots on the bulb expand into blotches under the papery outer layers; it looks like you handled the bulbs with sooty fingers. The cloves inside usually aren’t damaged and can be stored as usual in dry, cool conditions (i.e., not in a garden shed, which is much too damp). Unlike soil-borne root rots, Embellisia spores spread on the wind so although crop rotation is helpful, it won’t prevent all infections. If your garlic is otherwise healthy, you can use your own cloves for planting this fall.

Planting garlic: Which brings me to planting garlic, which is usually best done in October after the soil has become cool and wet. This reduces the risk of infection with Blue Mold Rot (Penicillium spp.), which thrives in warm, dry soil. Amend the soil with lime to raise the pH if your soil is acidic and incorporate a generous supply of compost. A complete organic fertilizer might be needed to improve fertility in new gardens and in beds where previous crops didn’t grow as well as they should have. Lightly comb the amendments into the top layer of soil and plant the cloves deep enough that tips are covered by soil. Spread a thick mulch of leaves or straw over the bed for winter.

Other planting this month: As warm-season crops vacate the space in my small greenhouse, I dig up enough leafy greens and salad plants from my garden to fill the greenhouse beds. This includes Swiss chard, as well as other leafy greens, lettuce seedlings, a parsley and arugula plant or two, sweet marjoram and other half-hardy plants. With care and in cool, cloudy weather, even mature chard plants can be moved into greenhouses or tunnels. Just dig deep enough to keep the long tap root intact and harvest the largest outer leaves to relieve the plants of leaf area until their roots get established. Smaller plants of lettuce and other leafy greens from mid-summer sowings are easier to transplant.

Strawberry plantlets that develop on runners from the main plants can be transplanted at this time of year to start a new bed. Ideally, you carefully removed runners all summer and left only enough to provide any new plants needed. In reality, however, strawberry patches often end up matted with runners shooting off in all directions with little plants and secondary runners criss-crossing the bed. Now is a good time to sort that out to avoid overcrowding and loss of production next year. Crowded plants compete with each other and their flowers often aren’t properly pollinated because they are jammed under leaves. From each main plant carefully follow along runners to find the little plants. Dig them if they have rooted in the soil and remove any secondary runners growing from them. If the little plants have good roots, transplant them directly into the new bed. If they aren’t well rooted, plant them in small pots of good soil, but leave them still connected to the runner from the mother plant until they are firmly rooted. It might be necessary to pin them down with a stone or a wire pin for a couple of weeks to keep them in the pot until roots develop. Cut the runners and plant the newbies in their permanent bed as soon as the roots are well grown.

Fall is an excellent time to plant fruit trees and berry bushes if you can find the varieties you want at plant nurseries at this time of year. Their roots become established over the winter, have a head start over spring planting and will require less water next summer. While the soil is still fairly dry, prepare any planting holes so that you can put the trees or shrubs into the ground as soon as you bring them home.

Upcoming Zoom presentation open to all: October 10, 7:00-8:30. Cut Your Losses: Managing Pests in Food Garden. The talk will cover how to prevent and manage common pests and other problems in vegetables and fruit using organic methods. Content will be tailored to cover pests that participants have requested and may include wireworms, aphids, root maggots, flea beetles, leaf-eating caterpillars, codling moth, fruit flies, pea leaf weevils as well as specific diseases. This second session is also a fundraiser for Salt Spring Island Farmland Trust in their Knowledge Series. To register: https://give-can.keela.co/linda-gilkeson-presents-whats-your-problem If you registered for the first session (Sept. 19), there is no need to register again, as you are already on the list to receive the link for the Oct. 10 talk (it will be recorded and the links to both talks will be sent out to all registrants after Oct. 10). If you are a new registrant, starting with the Oct. 10 session, you will also receive the links to both Zoom recordings.

Republished with permission from Linda Gilkeson’s Gardening Tips. See Linda’s website to sign up for her newsletter, purchase books, access free presentations and identify pests and diseases which may affect West Coast gardens.