Great Plains Gardening
June 6, 2003
I have gone through the entire month of May without sharing gardening tips from the CSU Extension Gardener’s Planning and Planting Guide…so, DID you: fertilize your cool season grasses (like turf type tall fescue and Kentucky blue grass) with one half to one pound of nitrogen per 1,000 square feet, adjust your mower blade height to 2 ½ to 3 inches, or apply crabgrass control if you had a problem with it last year? The June tips state that fertilizer can still be applied to the cool season grasses at the above rate and also the warm season grasses like buffalo grass and blue gramma can be fertilized at ½ pound nitrogen per 1,000 square feet.
In the vegetable garden your beans, summer squash, tomatoes, melon, cucumbers, peppers, corn and lima beans should have been planted after the last frost. May 11 saw 28 degrees at our house, and I planted garden May 12-15. Soil temperature dropped that week, but plants are coming along nicely. Did you know last frost in May averages May 10 for altitudes from 5,300 to 5,700 feet? At higher elevations, add one day for every 100 feet elevation. June is the time to stake peas and begin harvesting. Continue transplanting warm-season crops like tomatoes and peppers. Keep crops like lettuce and spinach harvested.
For the perennials/roses/ annuals section, May was the time to finish cleaning up roses. Based on soil test recommendations, all-purpose fertilizer should have been applied as needed. Bedding plants, such as petunias and geraniums, could be planted after the last frost and protected from wind and afternoon sun for a week after transplanting. In June, remember to keep plants deadheaded, that is, remove the spent flowers. These flowers may be dried and used for potpourri later in the season. Divide spring-blooming perennials. Plant frost tender bulbs such as cannas, begonias, dahlias, and gladiolas. Do not remove the foliage from tulips, daffodils and other spring bulbs. The dying foliage is building up the bulbs for next years bloom. Pinch back fall-blooming perennials every week until the 4th of July.
May was also the time to plant containerized trees and shrubs, taking care not to over water in heavy soils, apply integrated pest management strategies for care of trees, scout for aphids on new growth and hose down with water. If that does not work, apply soapy water on a shady day. That sums up the CSU tips for May and June.
In the previous paragraph I mentioned integrated pest management strategies (IPM). "IPM incorporates a variety of pest control strategies to manage a pest. The concept helps focus on the reduced reliance of pesticides. Examples of IPM tools include: #1, cultural methods such as planting dates, varieties, irrigation management, spacing, exposure to wind and sun, and plant species diversity; #2, climactic-consideration of temperatures, wind and rain, and timing of insect activity; #3, mechanical tools-the use of covers and barriers and traps; #4, bionaturals- predators, parasites, disease organisms, and beneficial nematodes, taking steps to preserve predators and parasites naturally occurring and importing and releasing predators and parasites; #5, pesticides- organic and synthetic or manufactured."
"Some important questions to ask about a pest include: What is the pest? Does it cause damage? Does the damage need to be controlled, considering the economic and aesthetic thresholds? What management options (#1-5 in the previous paragraph) are effective on the pest and when are they applied?"
"When a pesticide is considered, ask these important questions first. What pesticides are effective on this pest? Which have minimal health hazards? When are they applied to be effective? How are they applied to minimize health and environmental hazards? What is the re-entry period and application-to-harvest interval following application?"
"Answers to these questions often indicate that a pesticide is not warranted at this point in time. Less than 10% of landscape pest problems warrant pesticide use." (David Whiting, IPM/PHC Colorado Master Gardener Training)
Examples of pests that can be prevalent at this time of year include the following:
Miller moths are beginning to move to the mountains with warm weather so flights remain high.
Pine needle scale: crawler emergence typically begins around mid May, about the time of lilac peak bloom. Check infected plants.
Oystershell scale: crawler emergence typically occurs in late May. Check infected plants.
Bronzed cane borer/rose stem girder: Adults emerge from caneberries, currant, and rose.
Honey locust borer, bronzed birch borer: Adults may emerge by late May. Beetles fed on leaves and then lay eggs on bark.
Fruit tree leaf rollers: Leaf rolling may begin to be observed on many trees and shrubs.
Hackberry psyllid: Current season galls begin to be visible as small eruptions on leaves.
Cooley spruce gall: Current season galls are readily visible upon close inspection. Small nymphs are present in chambers of the gall.
Leaf curling aphids: Aphids curl the new growth of many plants at this time.
Imported currant worm: Larvae chew leaves of currant and gooseberry. Damage starts in the interior of the shrub.
European elm scale: Over wintered females feed intensively and begin to produce large amounts of honeydew.
European elm bark beetle: Adults emerge and feed on twigs. Most new transmission of Dutch elm disease occurs at this time.
Codling moth: Sprays after petal fall can help control the first generation. Monitor flights with pheromone traps.
Seedcorn maggot: Early planted beans, corn and melons are susceptible to seedcorn maggot damage.
Strawberry injuries: Millipedes and slugs tunnel the ripening berries.
Narcissus bulb fly: Adults stages emerge and lay eggs on narcissus, daffodils, and hyacinth.
Until next time…