Winter Crop Planting, Garlic Harvest, Ermine Moths Among Us

Time to start winter crop planting now and over the next few month: This week is good timing to sow seeds of Brussel sprouts and the varieties of winter cabbage that take over 120 days to mature (e.g., January King, Danish Ballhead, Langedijker Late Red). These need the whole summer and fall to make big, heavy heads for winter. Many main season cabbages take almost as long so check package descriptions to plan your sowing dates. The last week of May to first week of June is good timing to sow Brussels sprouts, but don’t leave it any later. This timing has sprouts developing in September and October, largely avoiding cabbage aphid damage to the sprouts as the aphids die off in the fall. Later sown plants risk not making sprouts at all because they are too late. If they don’t make sprouts this fall, they won’t do it in the spring because they send up flower shoots from where the sprouts would have been. If you seeded Br. sprouts earlier or set out plants from a nursery, just keep an eye out for aphids on the developing sprouts and keep them well sprayed off with water.

Make sure you have all the seeds you need for the rest of the season for your winter crops as seed suppliers do run out of things. Mid- to late June is a good time to sow the overwintering varieties of purple sprouting broccoli and cauliflower. The last crop of carrots, beets and other roots can be sown the first week of July; also in July, sow lots of leafy greens, kale, chard and in August you will want to seed fall and winter lettuce, Chinese cabbages and other spinach and frost hardy lettuce. If you don’t have a planting chart to remind you of these summer seeding dates you can print this one from my website.

Garlic Harvest? I have had more questions than usual about when to harvest garlic, partly due to the early season. How to know when to harvest? Last year my main crop garlic, usually harvested around mid-July, was harvested by June 27. My early garlic was out by June 10 (usually the 3rd week of June). So expect to harvest your garlic in June this year unless there is prolonged cool weather that slows things down. The necks of soft-neck garlic flop over like maturing onions when they are ready to harvest. This is not the case for hard-neck garlics--the ones with the flower stalk (called a scape) growing out of the middle of the bulb. For those, a sign they are ready is when 4 or 5 of the lowest leaves turn brown or yellow and dry up. You can also pull up a bulb and check whether the outer skin of the bulb is becoming thin and papery instead of being thick and spongy. There is no perfect harvest date so don’t get too worried about it: garlic could be harvested any time over several weeks. If you pull early, the bulbs might be a tad smaller than they might have been if you waited. Really late harvest (e.g., all the leaves have turned brown) increases the risk of disease infections in the bulbs, but even then, you might not see much of a problem. Do you have to remove the scapes? A study at WSU found that it doesn’t seem to make much difference in the size of the crop if the bulbs are growing in fertile soil; removing scapes may help bulbs grow larger in less fertile soil. Scapes are such a delicacy in a stir fry or made into pesto that most people do harvest them, but if you don’t get around to it, don’t worry about it. Do you have to stop watering two weeks before harvest? If you can, you save water and the bulbs might cure a little faster. It is not a requirement and may not be possible, depending on your irrigation system or a stray rain storm. I usually can’t turn off the water to my garlic beds because they are on the same system with other plants and my garlic keeps just fine. And some gardener with low lying, clay soils don’t need to stop watering because they haven’t started irrigating by the time garlic is ready to harvest.

Button-head Broccoli: Several people have told me that broccoli plants they set out this spring have sprouted tiny, premature flower heads. This is usually caused by injury to the cells at the growing point (called the apical meristem). Often caused by frost, it can also be caused by high temperatures, physical damage from rough handling or insect damage. Given the weather this spring, my bet would be on heat or a combination of heat and dry soil conditions while the plants were quite small (possibly while they were seedlings in the nursery). Button heads also occur on cauliflower, caused by the same conditions. I see this most commonly when people mistakenly plant summer varieties of cauliflower for a fall or winter crop. The cold days of late fall cause premature button heads and that’s the end of that cauliflower crop. Another growth disorder, ‘blind heads’, can happen to cabbage as well as broccoli and cauliflower. It has the same causes as button heads, but the damaged growing point means that heads don’t form at all—the leaves grow large and lush, but that’s all that happens. What will happen with those button-headed broccoli, I don’t know: they may form normal side-shoots after this, though I expect the central head is done for. My advice is to plant more broccoli while plants are still available from nurseries, just in case these plants don’t produce. There is even time to grow broccoli from seed if you start them now.

Web spinners: Some of you may have noticed webbing in apple or plum trees this month and feared that tent caterpillars were back. Breathe easy: those are ermine moth (Yponomeuta species) caterpillars. They make patchy, trailing webs along the branches as they eat leaves, causing little damage in most trees. Unfortunately, in 2 cases I know of on Salt Spring, plum trees have had so many caterpillars feeding on leaves that they have been seriously defoliated. The small caterpillars are largely done feeding by now so the damage is done. There are supposedly two separate species: apple ermine moth, which feeds on apple and crabapple, and cherry ermine moth, which feeds on cherry, plum and other trees. Sprays of BTK (Safer’s Biological Insecticide) work on these caterpillars, but there is no need to spray when there are only a few colonies, because many natural enemies attack the caterpillars. If you can reach the webbing, you can easily pull the caterpillars off of the branches, too. If your trees were seriously damaged (more than 25% of leaves chew up), however, be on the alert for developing colonies next year, starting in early May. Given the sporadic occurrence of ermine moths and their many natural enemies it is quite possible there won’t be any caterpillars, but if there are a lot of webs again, you may want to plan a BTK spray.

Salt Spring - Linda's List - purple cabbage

Salt Spring - Linda's List - January King web fmt

About Linda A. Gilkeson, Ph.D.

Salt-Spring---Linda-GilkesonLinda earned a Ph.D. in Entomology from McGill University in 1986, then moved to British Columbia to work for Applied Bio-Nomics Ltd., a company that produces biological controls. From 1991 to 2002 she worked for the provincial government, promoting programs to reduce and eliminate pesticide use. She was head of the provincial State of Environment Reporting Unit for the next six years, then the Executive Director of the Salt Spring Island Conservancy until the end of 2011. Linda now devotes her time to writing, teaching and consulting.

Linda has co-authored pest management training manuals for the government and organic gardening books for Rodale Press. She has self-published two books: Year Around Harvest: Winter Gardening on the Coast and West Coast Gardening: Natural Insect, Weed and Disease Control. Her recent book, Backyard Bounty: The Complete Guide to year-Round Organic Gardening in the Pacific Northwest, has become a BC best seller.

As a private consultant, Linda is a regular instructor in the Master Gardener programs in BC and is busy year around giving workshops on pest management and organic gardening.

Linda has served as President of the Entomological Society of Canada, the Professional Pest Management Association of BC, the Entomological Society of BC and the Salt Spring Island Garden Club. She was awarded a Queen’s Jubilee medal in 2003 and an outstanding achievement award from the Professional Pest Management Association of BC in 2005.

Follow Linda's work at­­­­­­­­­­­­­­­

May 30, 2016 2:12 PM

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