In areas where leaf miners are in abundance, covering plantings with insect nets or floating row covers will prevent the insects from laying eggs on your plants
Dear Helen: I have been gardening for many years but over the last five growing seasons my leafy greens such as chard, spinach and beet leaves have been damaged by leaf miners. I try to remove the ruined leaves when I see them, but more and more appear. Is there a way to successfully combat this harmful insect?
HS
Picking off individual leaves and destroying them only works as a control when leaf miner populations are low. In areas where the insects are in large numbers, covering the plantings with insect netting or floating row covers is the only surefire way to keep clean foliage on the plants.
Growing vegetables that need to be covered against insect pests in the same bed simplifies the cover. I grow beets and carrots (otherwise damaged by rust fly larvae) together in a 120cm wide bed for easy covering. Lightweight floating row covers designed for use as insect barriers do not require support structures. They stand out from the plants as they grow and “float” above the planting. Insect nets are sturdier and require support hoops or some other structure to hold them over the plants.
There are multiple generations of beet and spinach leaf miners over a growing season. The adult, tiny gray flies lay their eggs on the underside of leaves. The eggs hatch into larvae, which tunnel and feed between the upper and lower leaf surfaces, causing discolored spots and tunneling.
Crops can develop undamaged for years before insect pests discover and infest them. I successfully grew onion bulbs without protection for 25 years before a season came when onion flies discovered the planting and their larvae ruined each bulb.
Dear Helen: When watering my houseplants this winter, I noticed that the water draining into the pot saucers seems to be causing a problem with fruit flies. There aren’t many, but their presence confuses me as there is no fruit or veg nearby. How can I get rid of the flies?
NS
Small flies hovering around indoor plants are not fruit flies. They’re fungus gnats. The mosquitoes lay eggs in potting soil. The resulting larvae, small white worms, feed on organic matter in the soil and on plant roots.
Fungus gnats are commonly introduced indoors from eggs or larvae in the soil of newly purchased houseplants or plants brought back indoors after a summer outdoors. Sometimes they are in potting soil used for indoor plants.
For a number of years I have had significant infestations of fungus gnats in the homes of grafts I grow under grow lights. The infestation disappeared when I changed the purchased soil component of my seeding and transplanting mix.
A primary preventive measure is to check bag labels carefully to ensure that the potting mix you buy for houseplants (and indoor seeding and transplanting) is suitable for indoor use.
Fungus gnats live and breed in moist soil. It is helpful to allow a top layer of soil to dry before returning to moderate watering. To catch adults I used yellow sticky traps, which are available at garden centers and most seed and garden catalogues. The ones I’ve used are Safer’s Sticky Stiks houseplant traps
Small flies in kitchens, around fruit and compost bins are fruit flies. They arrive at the house with products bought or harvested. The flies are most troublesome in late summer and early fall when they are attracted to mature and rotting food.
Homemade traps made from apple cider vinegar with a drop of vegetable oil in shallow jars are good for keeping numbers down.
Yellow sticky traps attract and catch fruit flies and fungus gnats. In the fall I often put one or two next to the kitchen sink.
The sticky traps should only be used indoors. Outdoors, they will attract and destroy beneficial insects as well as flying pests.
GARDEN EVENT
Shabby in some way. “Seeding the Future” is the theme of the 19th annual Qualicum Beach Seedy Saturday, taking place from 10:00 a.m. to 3:30 p.m. at the QB Civic Center, 747 Jones St. The Great Hall will be filled with seed and plant vendors, with even more vendors and exhibits outside. There will be a seed swap, advice from master gardeners and the Seedy Cafe. A municipal truck will be available to receive unwanted pesticides and herbicides. Admission is by donation. qbseedysaturday.ca
hchesnut@bcsupernet.com
