Jul 1, 2024
Here's a list of things to keep an eye on this summer to avoid and manage pests of landscape trees, shrubs, and vines by incorporating these IPM strategies. Visit the Seasonal Landscape IPM Checklist for more information or to subscribe to their monthly emails.
Abiotic Disorders—Address your plants' basic needs to prevent or manage damage, such as that caused by poorly drained soils, frost, hail, herbicides, wind, and too much or too little water.
Ants—Manage around landscape and building foundations, such as using insecticide baits and trunk barriers.
Aphids—Spray a strong stream of water on small plants or apply insecticidal oils and soaps. Look for and conserve natural enemies like predaceous bugs, lacewings, lady beetles, and syrphids.
Camellia, citrus, gardenia, grape, and other plants adapted to acidic soil—If leaves are yellowing (chlorotic) between green veins, plants may benefit from foliar or soil application of iron and zinc chelate and mulching.
Cherry spotted wing drosophila—Harvest early; apply spinosad when the fruit develops any pink color.
Citrus—Monitor for damage and pests such as leafminers and scales.
Clean up mummies, old fruit, and nuts in and under trees to avoid harboring pests.
Coast redwood dieback—Check for drought-stress-related maladies such as abiotic disorders, bark beetles, fungal diseases, and spider mites. Deep water trees and apply mulch.
Codling moth of apple and pear—Bag fruit. Promptly remove infested and dropped fruit. Apply insecticides only if precisely timed.
Compost—Turn and keep it moist. Remember to add a carbon source such as straw or wood shavings.
Cover fruit trees, berries, and grapes with netting to exclude birds and other vertebrate pests.
Deter borers—Deep water trees adapted to summer rainfall, e.g., fruit and nut trees. Protect trunks and roots from injury and avoid pruning, except for hazardous trees and certain pests and plants that warrant summer pruning. Paint trunk and scaffolds with white interior latex paint diluted with equal water.
Eutypa dieback and gummosis—Prune apricots and cherries during dry days instead of winter pruning to avoid these diseases.
Fertilize caneberries, citrus, deciduous fruit trees, palms, and heavily-flowering shrubs with slow-release product if not done in March or April.
Fire safe landscape—LEAN: Thin out thick vegetation and eliminate fuel ladders that allow fire to climb up trees. CLEAN: Mow grasses and trim shrubs. Remove dry, resinous, or dead plants and flammable debris. Cut branches back 15 to 20 feet from buildings. Use non-combustible surfaces for walkways, patios, and driveways. GREEN: Landscape using low-growing, non-woody plants.
Grape diseases—Monitor for powdery mildew, Eutypa dieback, Phomopsis cane, and leaf spot. Prune, remove, or treat as appropriate.
Implement disease and insect control for apples, pears, stone fruits, nut trees, and deciduous landscape trees and shrubs such as roses.
Irrigation—Adjust watering schedules according to the weather and plants' changing need for water. Check systems for leaks and broken emitters and perform maintenance as needed. Consider upgrading the irrigation system to improve its water efficiency.
Lightly prune roses to promote fall flowering.
Mosquitoes—Eliminate standing water, e.g., in gutters, drain pipes, and flowerpots. Place Bacillus thuringiensis subspecies israelensis in birdbaths and ponds to selectively kill mosquito larvae.
Mulch—Apply organic mulch where thin or bare soil beneath trees and shrubs.
Petal blight of azalea, rhododendron, and camellia—Remove and discard old flowers. Apply fresh organic mulch beneath plants.
Powdery mildew—If severe, e.g., on crape myrtle, grape, and rose, avoid fertilization and overirrigation. Prune during the proper time of year to increase air circulation and sun exposure.
Prune deciduous trees and shrubs that need pruning, e.g., apple, crape myrtle, pear, rose, spirea, and stone fruits. Make cuts properly to encourage good form and structure. Remove dead, diseased, and borer-infested wood. Except certain pests and host plants warrant summer pruning, e.g., shothole borer, apricot, and cherry.
Rose pests—Manage or take preventive actions, such as for aphids and powdery mildew.
Scale insects—If damage has been unacceptable, monitor the crawler stage, and when abundant, apply horticultural oil or another insecticide.
Spider mites - Irrigate adequately, mist leaf undersides daily, reduce dustiness, and spray horticultural oil or neem.
Stone fruit pests—Monitor for pests such as aphids, borers, brown rot, caterpillars, powdery mildew, and scale insects.
Weeds—Manage weeds using nonchemical methods such as hoeing, handweeding, mowing, or mulch.
Yellowjackets—Place Place out and maintain lure traps or water traps.