Crabgrass control and Tower Hill Update
Central Region (Boylston) – General Conditions: Weather remains unstable in typical April fashion. Cool, wet and rainy days are punctuated by an occasional warm sunny one. Minor bulbs such as Scilla and Chionodoxa, continue to bloom, while crocus, snowdrops and winter aconite have all but finished. More Narcissus cultivars are opening, and species tulips, and hybrids in protected location are beginning to bloom. Hellebores and Pigsqueak (Bergenia sp.) are in full bloom. White Forsythia (Abeliophyllum distichum); February Daphne (D. mezureaum); Winterhazel (Corylopsis spicata and C. pauciflora); Mountain Pieris (P. floribunda); Fragrant Honeysuckle (Lonicera fragrantissima and L. purpusii), Rhododendron dauricum; and some Boxwood (Buxus microphylla) are in full bloom. Pests/Problems: Vole activity seems to be on the rise.
Late April early May are the prime time for Pre-emergent Crabgrass Control, you should be scheduling your application now. Crabgrass is a tremendous competitor, vying for open space in our landscapes and even hardscapes. One Crabgrass plant that grows 2-3 feet in diameter can produce 100,000 seeds, so you can count on them being everywhere. Crabgrass germinates at a soil temperature of 54 degrees F, which usually occurs in mid-May. Often Forsythia bloom is noted as an environmental cue for application. Actually, it is the bloom drop which coincides with crabgrass germination. Getting the application down in early April waste some of the protection you get. Chemicals that control seedling germination are tied up in the top half inch of the soil, when the seed germinates the crabgrass control, which is a rooting hormone, kills the root and stops the seed from germinating. These Crabgrass Control products last for 6-8 weeks of control. If you had a large Crabgrass problem last year you could consider a second application to extend the coverage time of the treatment, this will extend the coverage into July. It can be tough to find Crabgrass Control alone as most Step 1 products are a combination of Fertilizer and crabgrass control. The second application can be used at a half rate to boost the residual control from the first application. Crabgrass Control needs to be watered into the soil within 7-14 days after application with a ½ inch of water or rainfall. The Crabgrass Control and fertilizer products are not effective until activated by rainfall or irrigation. Typically, raking or mowing the lawn after the application is watered-in will not alter the effectiveness. However, thatching, aerating or seeding activities that vigorously disturb the top ½ inch of soil may destroy the protective barrier.
Dimension is the name of one product that also has some post-emergent control of Crabgrass plants in the 2-3 leaf stage, so if you think you are a little late getting this application down, use a Fertilizer which contains Dimension. We get good crabgrass control with applications from early April until Memorial Day. Most of the lawns we take care of don’t have a large population of Crabgrass from last year and do well from year to year. A healthy lush green lawn will help shade the Crabgrass plant and prevent it from being a nuisance in the lawn. The big problem areas for Crabgrass are along asphalt and curbs, this is because the black surface absorbs the suns heat and warms up the soil faster in these areas and the crabgrass germinates earlier in these spots. I always recommend doing Crabgrass and Broadleaf Weed Control in the Spring, and seeding in late August when there is less completion from Crabgrass. Any Crabgrass that germinates in August will not become a mature plant and produce seeds. Tupersan is a selective Crabgrass control, to be used when seeding desirable grasses. It is twice as expensive as non-selective control products and needs to be applied 2-3 times. I gave up using it and switched to post-emergent products like Acclaim and Drive, to control the Crabgrass after Spring seeding. Spring seeding will always lead to a lot of Crabgrass, unless you are seeding shady areas where Crabgrass does not do well. I feel that Crabgrass Control in the Spring is one thing that is very important in developing.
Steve Crowe is an Honors Graduate of the University of Massachusetts, College of Natural Resources and the Environment, major in Turf Science
Massachusetts Certified Landscape Professional since 1993
Massachusetts Certified Horticulturist since 1984
Massachusetts Pesticide License, also requiring continuing education to retain