What to do now
Mildest step first.
- Match the damage: pinholes, ragged holes with slime, pale blotches, or large holes with droppings.
- Pinch or pick off mined leaves and put them in the trash, and rub off clusters of white eggs under the leaves.
- For slugs, check plants after dark with a flashlight and pick them off, or trap them under a raised board.
- Cover the next sowing with row cover right after planting, in a bed where spinach, beets and chard didn't grow last year.
Match the damage
Several pests eat spinach in spring, and each leaves a different mark. Small round shot holes mean flea beetles. Irregular holes with smooth edges, plus silvery slime trails, mean slugs or snails. Pale or tan blotches, where the leaf has gone and papery but isn't chewed through, mean leafminers, which feed inside the leaf. Large ragged holes with dark droppings point to caterpillars. Turn several leaves over, and if you find nothing in daylight, look again after dark with a flashlight. If holes are showing up on many kinds of plants, the page on holes in kale, cabbage and other vegetable leaves covers more culprits.
Leafminers
Spinach leafminers and beet leafminers are close relatives that attack spinach, beets and chard. Washington State University's HortSense explains that the maggots make narrow mines inside the leaf that enlarge into pale blotches, leaving damaged leaves distorted. The University of Maryland Extension says the flies emerge in spring and lay easily seen, bright white eggs in groups of 4 to 8 on leaf undersides, and that the fed-on areas start out opaque and later turn brown. One life cycle takes 30 to 40 days, with three to four generations a season, so a light spring problem can grow. WSU suggests pinching leaves to kill the maggots inside and removing infested leaves, into the trash, as soon as you notice them. Trim mined patches off leaves you harvest.
Flea beetles
Flea beetles are tiny, about 1/10 inch, and jump when disturbed. The University of Maryland Extension lists spinach and beets among the crops they feed on, though eggplant and cabbage-family crops are their favorites. Their feeding riddles leaves with small holes in a shot-hole pattern. Maryland says they are among the first insects active in spring, favor hot, dry weather and target tender seedlings, so new sowings take the most harm. secured to the ground keeps them off, and Maryland also lists kaolin clay sprays, which coat leaves in a particle barrier and need reapplying after rain.
Slugs and caterpillars
Slugs feed at night and on cloudy or foggy days, and hide under boards, stones and debris in the daytime. The UC Statewide Program describes their damage as irregular holes with smooth edges, and says silvery slime trails confirm them. Handpick them after dark, or lay a board about an inch off the ground, check it every day and destroy the slugs underneath. UC IPM notes that iron phosphate baits are safer for use around dogs, children and wildlife than other baits. Caterpillars leave larger, rougher holes, often with droppings on the leaves below; Clemson Extension lists cabbage loopers, corn earworms and diamondback moth caterpillars among spinach pests, along with cutworms and aphids. Pick caterpillars off by hand.
Next sowing
Leafminer maggots drop to the soil to pupate, so new flies come up from beds that were infested. WSU suggests rotating crops, avoiding replanting where crops were infested the year before, and covering plants with floating row cover before the flies emerge in spring. It cautions against laying row cover over soil that had leafminers the previous year, since flies coming up from that soil end up under the cover with the crop. Maryland and WSU both advise controlling weeds that host leafminers, including lambsquarters, chickweed and pigweed. Clearing boards and debris from the bed edges removes slug hiding places, and the same row cover keeps flea beetles off young plants.
Read the whole label first: it must list your crop, and its directions (amount, timing, gear, bees, days before harvest) are the law. If this page and the label differ, follow the label.
- Leaf MinerPale winding tunnels or blotches inside leaves, with tiny fly larvae visible inside the mine.
- Flea BeetlePinhole shothole damage across leaves with tiny jumping beetles that scatter when touched.
- SlugIrregular holes in low-growing plants overnight, with silver slime trails left behind on leaves and soil.
- Cabbage LooperRagged holes in brassica leaves made by a pale green caterpillar that loops its body as it moves.
- Eastern Cottontail RabbitStems clipped cleanly at a 45-degree angle near soil level, with small round droppings nearby.
- What is eating holes in my kale, cabbage and other vegetable leaves?On kale and cabbage, small round shot-holes suggest flea beetles, and large ragged holes with frass (dark green droppings) point to cabbage worms (imported cabbageworm). On other crops, ragged holes with slime trails mean slugs, and lacy leaves point to beetles. Check both sides of leaves, and look again after dark.
- Why is my spinach bolting?Spinach bolts when spring days get long, and warm weather speeds it up. Once a center stalk rises, harvest the whole planting. Next time sow earlier, choose slow-bolting varieties, or grow it in fall.