Home & Garden

Watch out for garden pests, they can be hard to spot

Snails cluster on a plant leaf. Snail damage is evident on the leaves.
Snails cluster on a plant leaf. Snail damage is evident on the leaves. Fresno Bee file

We often see pest damage in our gardens but can’t find the pests. A little detective work to identify the type of damage and the pest that causes it can help us discover where they’re hiding.

Elinor Teague

Snails and slugs provide a good example of the hunt method of pest control since after feeding at night they leave silvery slime trails that can be followed back to their daytime hiding places. It’s easy to handpick a large group and drop them into a bucket of soapy water or use the ‘big foot’ method to kill them. Iron phosphate snail and slug baits can be applied near the hiding places for best results.

Cutworms are moth larvae/caterpillars that emerge in spring to feed on tender new seedlings. Cutworms burrow into the top inch or two of soil during the day and come out at night to chew uneven round holes in flower petals and the new leaves of most garden crops. They often bite right through small stems of seedlings and transplants at soil level.

Handpicking cutworms at night using a flashlight to find them works well as does lightly cultivating the soil during the day near new transplants and seedlings to uncover them as they are sleeping. The caterpillars are a mottled gray or soil-colored light brown and 1 to 2 inches long. When uncovered, cutworms curl into a distinctive C-shape.

Make 6- to 8-inch collars out of paper towel cardboard rollers and use them to protect seedling stems. Bt or Bacillus thuringiensis or spinosad sprays applied on cutworms as they feed will kill cutworms on larger plants.

Aphid species are mostly specific to the plants they feed on. On roses, rose aphids usually cover the stems and new buds in spring. On hackberry trees, the woolly hackberry aphid feeds on leaves throughout the growing season; their excessive amounts of sticky ‘honeydew’ cause a real mess underneath untreated trees. Heavy aphid infestations feeding on new leaves in spring can cause the leaves to curl, hiding the aphids. If you’re seeing curled leaves on your plants or sticky honeydew on them (or ants on your plants), pick off a leaf and open it to check for aphids. The aphids can be washed off lower leaves or small trees with a fairly gentle stream of water (you don’t want to tear the tender leaves) or neem oil or another lightweight horticultural oil can be applied to smother the aphids. Systemic insecticides can be used to treat taller trees for severe aphid infestations that can weaken the tree, but first try correcting any cultural problems, especially over- or under-watering, that cause the trees to be stressed and attract pest insects.

Red spider mites don’t hide very well. They congregate on the undersides of leaves in summer, especially dusty leaves, feeding on plant juices. You can easily spot stippling or lighter spots on the tops of the leaves and their webbing on the undersides. Keep plants as free of dust as possible by regularly rinsing both upper and undersides of leaves with water. Applications of neem oil or other lightweight horticultural oils will smother red spider mites.

Elinor Teague: etgrow@comcast.net