Extension

Trees and Shrubs

• Proper watering of newly planted trees and shrubs often means the difference between success and replacement.
• Remove any winter-damaged branches or plants that have not begun to grow. Prune spring flowering plants as soon as they are finished blooming. (HLA-6404, HLA-6409)
• Control of powdery mildew disease can be done with early detection and regular treatment. Many new plant cultivars are resistant. (EPP-7617)
• Fungicides for leaf spot diseases of ornamentals can be applied.
• Diplodia tip blight fungicide applications should be applied at bud break.

Flower Beds

• Most bedding plants, summer flowering bulbs, and annual flower seeds can be planted after danger of frost. This happens around mid-April in most of Oklahoma. Hold off on mulching these crops until spring rains subside and soil temperatures are in the low to mid 60s.
• Harden off transplants outside in partial protection from sun and wind prior to planting.
• Lace bugs, aphids, spider mites, bagworms, etc. can start popping up in the landscape during the later part of April. Keep a close eye on all plants and use mechanical, cultural, and biological control options first.
• Let spring flowering bulb foliage (daffodil, tulip, etc.) remain as long as possible before removing it.
• Pinch back leggy annuals to encourage branching and fuller growth.
• Water newly planted annuals frequently until established, then transition to deeper, less frequent water.
• Be alert for both insect pests and predators. Some pests can be handpicked without using a pesticide. Do not spray if predators such as lady beetles are present. Spray only when there are too few predators to be effective.
• Nutsedge plants can become visible during this month but wait until May for treatment.

Vegetables

• Transition from cool-season crops to warm-season crops as temperatures rise.
• Cucurbit crops and okra can be planted towards the end of April.
• Cover cucurbit crops with a floating row cover to keep out insect pests. Remove during bloom time to allow for insect pollination.
• Apply fertilizer according to soil test results.
• Incorporate compost or other organic matter into vegetable garden beds for improved soil health.
• Pay close attention to the forecast and look for potential late freezes. The
• Plant vegetable crops in successive plantings to ensure a steady supply of produce rather than harvesting all at once.
• Watch for cutworm damage and add flea beetle scouting to your list of activities in the vegetables garden.

Lawn and Turf

• Warm-season grass lawns, such as Bermudagrass, zoysiagrass or, in southern Oklahoma, St. Augustinegrass, can be established beginning in mid-April from sprigs, plugs or sod. (HLA-6419)
• Fertilizer programs can begin for warm season grasses in April. The following recommendations are to achieve optimum performance and appearance of commonly grown species in Oklahoma.

-         Zoysiagrass: 3 lbs N/1,000 sq. ft./year

-         Buffalograss: 2 - 3 lbs N/1,000 sq. ft./year

-         Buffalograss/grama mixes: 3 lbs N/1,000 sq. ft./year

-         Bermudagrass: 4-6 lbs N/1,000 sq. ft./year

-         Centipedegrass: 2 lbs N/1,000 sq. ft./year

-         St. Augustinegrass: 3-6 lbs N/1,000 sq. ft./year

• When using quick release forms of fertilizer, use one pound of actual nitrogen per 1,000 sq. ft. per application; water in nitrate fertilizers. (HLA-6420)
• Mowing of warm-season lawns can begin now (HLA-6420). Cutting height for Bermuda and zoysia should be 1 to 1½ inches high, and buffalograss 1 ½ to 3 inches high.
• Damage from Spring Dead Spot Disease (SDS) becomes visible in bermudagrass (EPP-7665). Perform practices that promote grass recovery. Do not spray fungicides at this time for SDS control.
• Grub damage can be visible in lawns at this time. Check for the presence of grubs before ever applying any insecticide treatments. Apply appropriate soil insecticide if white grubs are a problem (EPP-7306). Water product into soil.

Fruit and Nuts

• Don’t spray insecticides during fruit tree bloom or pollination may be affected. Disease sprays can continue according to schedule and label directions. (EPP-7319)
• Control cedar-apple rust. When the orange jelly galls are visible on juniper (cedar), following a rain, begin treating apple and crabapple trees with a fungicide. Treat hawthorns accordingly. (EPP-7319, EPP-7611)
• Fire blight bacterial disease can be controlled at this time. Plant disease-resistant varieties to avoid diseases.
• Continue spray schedules for disease prone fruit and pine trees.

General

• Hummingbirds arrive in Oklahoma in early April. Get your feeders ready using 1-part sugar to 4-parts water. Do not use red food coloring.
• Keep the bird feeder filled during the summer and help control insects at the same time.
• Schedule a group tour of the OKG Studio Gardens in Stillwater between the first of May and late October!
• Clean out the water garden and prepare for season. Divide and repot water garden plants.
• Begin feeding fish when water temperatures are over 50 F.