Sandy Perrin

As summer approaches, it's crucial for gardeners to implement effective pest and disease management strategies to protect their plants. Here are the latest updates and recommendations for various pests:

It's time to apply the first-generation Codling moth spray. Gardeners have options ranging from less toxic spinosad or neem to harder pesticides like malathion and permethrin. For optimal results, apply sprays in the evening. For those in higher elevations such as the Rattlesnake area, it's best to wait another week.

Tent caterpillars are increasing in number and are now too large for effective treatment with Bt (Bacillus thuringiensis).

Juniper scale is hatching and in the crawler stage, making it an ideal time for treatment.

Preventative treatments for healthy pine trees against Mountain Pine Beetle are necessary. Apply the pheromone Verbenone (available at Rob Dillon Tree Service in Missoula) or spray trunks with carbaryl, especially on trunks with a diameter less than 5 inches. Keep pine trees well-watered during hot, dry weather.

Apply preventative sprays to the trunks of healthy birch trees with liquid carbaryl spray. This treatment is ineffective on already infested trees.

Poplar borer adults are emerging and will soon lay eggs in new aspen trees. Apply trunk insecticide sprays to healthy aspens to prevent attacks.

Aphid populations are increasing. Check trees and shrubs like plum, cherry, caragana, maples, and roses. Treat aphids with insecticidal soap or a combination of neem and insecticidal soap if populations are high.

Leafhoppers continue to cause white stippling on roses, apples, and Virginia creeper. Treat with insecticidal soap plus pyrethrin. For rose curculios, dark weevils that damage rose foliage, neem is the least toxic option.

Slugs and earwigs are damaging seedlings and leafy greens. Use traps to manage these pests effectively. Slugs can be trapped with flat boards or beer traps, and earwigs with low-sided cans filled with oil.

Wilting spruce tree terminals indicate White Pine Weevil larvae. Remove and destroy wilted tips immediately.

Use sulfur or copper sprays for fungal diseases and copper for bacterial diseases like Fireblight. Avoid watering leaves, branches, and stems to prevent further infections.

Garden Plant Diseases

Check tomatoes, potatoes, cucumbers, and squash for fungal and bacterial symptoms such as circular brown spots or dark, curled leaf margins. Ensure plants are well-watered and fertilize weekly to help them outgrow flea beetle attacks.

Don't miss the peony gardens at the University of Montana, which are in full bloom this week! Stay vigilant and proactive in your garden to ensure a healthy and productive growing season.

Sandy Perrin is with the Missoula County Extension Office.