May Gardening Calendar - Colorado State University Extension Tri River Area Mesa Delta Montrose Ouray Counties

Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
Week 1
Average last hard frost of 28 ^oF. in Paonia (elevation - 5690 feet) is May 2 Average last spring frost of 32 ^oF. in Uravan is May 1 Ascochyta Leaf Blight of Turf: Straw-colored patches of diseased turf will appear on drought-stressed turf during May.	Powdery Mildew: of turf will begin to appear in shaded areas. Treatments may be needed. Slime flux is starting to flow from many trees. This bacterial infection is in the heartwood of the tree and very difficult to cure. Do not drill a hole to relieve the pressure as this will spread the disease throughout the tree.	Average last spring frost of 32 ^oF. in Grand Junction (elevation - 4620 feet) is May 3 Begin: a lawn watering schedule that is deep and infrequent based on the water needs of the turf.	Juniper Rust: Gelatinous fruit bodies appear on juniper following wet weather. Over watering trees and shrubs in the spring is a common problem. While these woody plants would like a thorough soaking on occasion, it is important that these plants not be kept wet all the time.	Call the Dial-a-Garden Message weekly at 970 244-1706 to learn the latest for the week. Cytospora Canker: Peak period of spore production and initiation of new infections on aspen, cottonwood and willow.	Apply treatment for Ash Borer between now and May 10 Asparagus Beetles: Adults emerge and lay eggs on spears	Leafcurling Aphids: These aphids will start to appear on plums, peach, honeysuckle and other plants. Inspect and treat if needed.
Week 2
Average last spring frost of 32 ^oF. is May 7 in Gateway and May 8 in Paonia (elevation 5690 feet). Lawnmower Injury: Avoid damage to the base of trees and shrubs with lawnmowers and string-weeders.	Elm Leaf Beetle: Adults return to trees and chew holes in leaves. Hackberry Psyllid: Adults return to trees and lay eggs on the emerging leaves. Sprays to protect Apple and Pear fruit from Codling Moth should be started about two weeks after petal fall.	Honeylocust Pod Gall Midge: Adults begin laying eggs on new growth. First generation begins. Gardeners often find that apple and crabapple fruit is a nuisance. Sprays to remove fruit must be applied within 30 days following full bloom.	If planting trees, shrubs, or flowers into an area that has fresh wood chips or bark mulch worked in, add nitrogen fertilizer to provide the microbes with the necessary nitrogen to breakdown the wood particles. A handful of ammonium nitrate or ammonium sulfate per estimated bushel of wood chips should be adequate.	Average date of last hard frost (28 ^o F.) in Collbran is May 11 Check Transplants: Carefully examine plants prior to planting to avoid introducing whiteflies, and other pest problems.	Average last spring frost of 32 ^o F. in Fruita is May 10; Montrose is May 12; Delta is May 14 Fertilize Cool Season grasseswith 1/2 pound of Nitrogen per 1000 square foot area of turf	Average date of last hard frost (28 degrees F.) in Ouray is May 13 As the candles of pines begin to elongate, snap off part of these candles to slow the growth of the tree. This is sometimes necessary when a pine is growing longer on one side than wanted.
Week 3
Honeylocust Plant Bug: Nymphs have hatched and begin to damage new growth. The fruit on a peach tree should be thinned to 5 to 8 inches between fruit. This allows for the proper development of the remaining fruit.	Codling Moth: the insect that causes wormy apples and pears. Check with Dial-a-Garden Message (244-1706) regarding spray dates.	Grackles and Starlings feeding in lawns typically indicates an infestation of Sod Web Worms. These birds often control this insect eliminating the need of a pesticide spray.	Honeysuckle Witch's Broom Aphid: Treatments should be applied soon to bush honeysuckle to prevent damage. Cut out previous year's dead and distorted twigs.	Sprays to protect apple & pear fruit from Codling moth may be needed every ten to fourteen days depending on the insecticide you use. Refer to the product label for specifics.	Cooley Spruce Gall: Eggs hatch and young nymphs move to feed on new growth of spruce trees. Galls start forming.	Tick Season Begins: The next two months are the peak season for tick activity and spread of Colorado tick fever.
Week 4
Oystershell scale: Crawler emergence typically occurs in late May. Check infected plants for this pest and treat if presence noted.	Some plants, such as clematis, require cool roots to do well. The Clematis also requires full sun. Large flat rocks placed over the root zone of the Clematis will help keep the roots cool	Three to four inches of a good mulch around plants is recommended. Be sure to soak the ground before applying the mulch to cool the ground. Be careful that you do not over water plants in areas that are mulched. Check the soil moisture content under the mulch before watering.	Slugs: Damage to seedlings and transplants may begin to occur. Check plants with a flashlight about 10:30 p.m. to confirm the problem. Damage could be due to climbing cutworms.		Leaf hoppers feed on virginia creeper and grapes. These one-eighth inch flying insects suck the juices from the leaves giving the leaf a speckled appearance. Severe feeding injury can cause the leaves to turn white and die. A spray of an insecticidal soap, Diazinon [Note: no longer legal after December 31, 2004 see http://www.ok.gov/~okag/forms/cps/epaagree.pdf)> or malathion works well. The insecticide Sevin does not work on this insect.	Caterpillars eating the needles off pine trees are often the larvae of a wasp-like insect called a sawfly. The insecticides Sevin, Diazinon [Note: no longer legal after December 31, 2004 see http://www.epa.gov/pesticides/op/diazinon/agreement.pdf)> and malathion will control this insect. Use a wettable powder formulation and not the liquid concentrate. The liquid concentrates contain a wax remover that will likely damage the needles. The wettable powder formulation is mixed with water and applied as a spray.
Week 5
	Prostrate Spurge seed germinates in late May to Early June. A preemergent herbicide could be applied now to prevent problems with this lawn weed.	Average last spring frost (32 ^oF.) for Paonia (elevation 6200 feet) is May 28.	Avoid the planting of any of the Loosestrifes as this flower can become a serious weed along our streams destroying habitat of native plants and animals.	Ripening Strawberries are susceptible to attack by Millipedes and slugs.	Average last spring frost of (32 ^oF.) for Colbran and Ouray is May 29.