This looks like thrips damage. They’re a common pest on many different flowers, fruits and vegetables in local landscapes. Onion thrips and western flower thrips cause damage on the young leaves, buds, blossoms and fruitlets of a wide variety of vegetables, fruits, flowers and landscape plants when they feed or insert eggs into plant tissues. The damage they cause is easy to see after the leaves and flower petals expand, but the thrips themselves are very tiny and can be hard to see without the help of a hand lens.

Thrips damage on leaves can look like stippling, discolored or pale spots on leaves or petals, deformed petals or a silvery appearance to leaves. This damage is sometimes just cosmetic. For example, your pea pods aren’t picture perfect but they’re still edible. For orchardists and cut flower growers, thrips feeding can leave the damaged flowers and fruits unmarketable. Heavy thrips infestations can reduce the vigor of plants and affect crop yield. Thrips can also transmit plant viruses.

Good garden sanitation is important in controlling many pests, and thrips are no exception. Don’t let leaf litter and plant debris accumulate in your garden. Weeds can be an early season host for thrips, and they’ll move from weeds onto their preferred fruit and vegetable crops when they are available. Keep weeds under control in the areas around your landscape to reduce alternate hosts for the thrips.

Because thrips feed on young leaves, bud and blossoms before the damage is noticeable it’s helpful to do preventive insecticidal sprays early on your pea crop if you’ve had thrips problems in the past. Pest problems are easier to control if they’re managed sooner rather than later. If you don’t want to do preventive sprays, it will be worth the effort to scout frequently and use control methods as soon as you notice the first signs of damage on your pea plants to protect the new growth as it comes on.

Courtesy Meredith Seaver, USU Extension

Thrips can be dislodged by rain or overhead irrigation. If you’re using drip irrigation, gently hosing off plants can remove many of the thrips from your pea plants.

Insecticidal soap or 1% horticultural oil are effective spray controls for thrips, but you must give thorough coverage each time you spray and repeat the sprays every four to seven days. These products are safer for the natural predators of thrips and because they aren’t poisons, thrips don’t develop resistance to them.

These sprays can damage leaves if the spray is wet when temperatures are high. This may not be a problem for cool season crops like peas, but if you need to control thrips on other crops, spray in the early morning or later in the evening to give the sprays plenty time to dry before the heat of the afternoon. Insecticides with the active ingredient Spinosad are also very effective.

Thrips feeding in the rose bud damages the edges of the petals, preventing the edges from expanding fully along with the rest of the petal.

Thrips will feed on tiny fruitlets and the damage can be extensive as the fruit expands. This is very noticeable on nectarines.

Onions are a common host for thrips, and their damage can be seen on the leaves of the onions. They will also feed between the onion layers at the neck of an onion and can continue to feed after harvest and during storage.

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