Garden pests

Credit: Carolyn Herriot

cleavers.jpg

Problems In the Garden

Cleavers (Photo)
Cleavers (also known as bedstraw) is a cunning annual, reproducing by seed borne on clinging trailing stems. A single plant can produce 3,500 grey-brown bristly seeds! As cleavers prefers damp soil the seed becomes dormant in dry soil, and can remain viable from 1 to 3 years.
The 2 to 4-foot long trailing stems are square, with short downward-pointing hooks. Cleavers is easily spread around the garden by bristly stems and seeds, which cling to clothing, gardening equipment and the hair of animals. So you can see why this plant is not invited into my garden!

Sowbugs and pillbugs are similar-looking pests, more akin to crayfish than insects. They are distinguished as the only Crustaceans adapted to living on land. They have gills which need constant moisture, and for this reason are primarily nocturnal thriving only in high moisture conditions. Their armadillo-like bodies are convex above, but concave underneath. The way to tell a sowbug from a pillbug is that pillbugs roll up into tight balls when disturbed, (for which they are also called “roly-polies”).

Sowbugs and pillbugs are slate-gray scavengers, about 1/2 inch long, that eat decaying leaf litter and vegetable matter, but also feed on the tips of young plants – so I consider them to be pests! Anywhere damp is a good breeding place. They are commonly found under mulch, compost, boards, stones and in flowerpots. Sowbugs and pillbugs carry their eggs in a pouch for about three weeks until they hatch, and continue to carry the young for a few months after hatching. They may have several broods in a year!

There are 4 main species of leafminer which attack vegetables and ornamentals in North America. Severe damage to leaves can cause cosmetic damage and reduce their photosynthetic ability. Leafminers are small (2-3mm), shiny black and yellow flies which lay eggs into leaves, so that larvae feed between leaf surfaces. Larvae tunnel within the leaf tissue forming characteristic ‘mines’, then cut a semi-circular and drop to the soil to pupate.

Pupae can survive up to 90 days when temperatures are cool, or host plants, such as aquilegia, beets, Swiss chard and spinach are not available. The life cycle could be as short as 14 days at 30°C or as long as 64 days at 14°C.

Control:
Remove crop debris and any infected plant material from the garden.
Crop rotation is an effective management tool. Alternating leafminer susceptible crops with leafminer resistant crops reduces the population.
Many wild plants act as hosts for leafminers. Maintaining weed free conditions in the garden is recommended.
I find one spraying of infected leaves with Safer’s Trounceä (which contains pyrethrins) does the trick. Leafminers are known to develop resistance to insecticides quickly.
Companion planting encourages diverse populations of beneficial insects, which introduces natural parasites that reduce leafminer populations.

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