Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Hort Update for the week of 5/18/2009
|Current Problems:||Major Symptom:|
|1. Henbit & speedwell||Herbicide applications are not recommended for winter annuals now.|
|2. Ground ivy||Perennial broadleaf. Best controlled with herbicide applications in Sept.|
|3. Snowdrift slow-down||Turfgrass under snowdrift areas have been slow to begin active growth.|
|4. Slow green-up of Fescue||Spring freeze injury. Some thinning may occur. Overseed in September.|
|5. Tenacity herbicide||May be available in 2011 for nimblewill control.|
|6. Sod webworm in Western Nebraska||Overwintering larvae causing some early season damage.|
|7. Preen Organic (corn gluten meal)||Pre-emergence organic herbicide for lawns, flowers, & vegetable gardens.|
|8. Emerald Ash Borer||Most recent confirmation is 5 miles east of eastern Iowa border, in the LaCross, WI area|
|9. Pine Sawflies||Foliage eaten off terminal ends of evergreen branches.|
|10. Bagworm||Wait until after egg hatch to apply insecticides sometime in June.|
|11. Grass control in flower beds||Grass-Be-Gone and Over the Top are recommended herbicides.|
|12. Winter dieback/dessication||Wait until June 1st to prune damaged growth on conifers.|
|13. Transplanting perennials||Transplant fall or summer bloomers in spring.|
|14. Preen for weed control- Tips||Must be watered in and three applications needed.|
|15. Apple twig borer in grapes||Found in grapes in western Nebraska.|
1. Henbit and Speedwell are winter annuals. Most seed germination took place last September into October. These plants will bloom in spring, produce seed and die. Post emergence herbicide applications are not recommended at this time. Hand-pull weeds if feasible. Determine why turfgrass is not competing with winter annuals and change cultural practices to promote grass density. Where herbicide control is needed, apply a preemergence herbicide in early September.
2. Ground Ivy is a perennial broad-leaf weed that can appear similar to Henbit when blooming in spring. Positive identification is important. Post emergence herbicides applied at this time of year can burn back foliage but regrowth usually occurs. Applications made in September with combination herbicides are most effective in controlling ground ivy.
Midwest Turfgrass Weed Identification and Control Web site. Scroll down to Ground Ivy, http://www.turf.uiuc.edu/weed_web/index.htm
3. Delayed growth beneath snowdrifts- In some areas, Kentucky bluegrass has been slow to begin active growth where there had been deep snowdrifts. Snow mold diseases have not been found on most of these sites. The turfgrass should recover. Where thinning occurs, core aerate and overseed this fall.
4. Slow Green Up of Fescue lawns is being contributed to spring freeze injury in March. Thinning of Fescue lawns could occur. These areas can be overseeded in September to increase grass density. Core aerate before overseeding this fall.
5. Tenacity Herbicide Update- This product will not be on the market for homeowner use for a few more years, possibly 2011. Work is continuing with the manufacturer to test the product. The active ingredient is mesotrione. In 2008, it was available for use on golf courses & sod farms. A Federal label was EPA approved in early 2009 for commercial application to parks & residences. State approvals are pending.
6. Sod Webworms overwinter as partially grown larvae. In spring, they move to the surface and feed until mid to late May when they pupate and emerge as adults. Most sod webworm damage occurs in July and August in Nebraska. When overwintering populations are high, some damage may occur to lawns in spring. This year, damage is being reported in the Panhandle.
The close clipping of grass blades by sod webworm does not kill turfgrass directly but exposes the crown to heat stress; thus, injury is much worse during hot, dry weather. If damage is not too severe, lawns recover from spring feeding without treatment.
If webworm is suspected, get down on your hands and knees and part the grass with your index fingers to look for small green pellets. The pellets are the larvae's excrement and indicate they are present. The caterpillars have dark heads and light-brown spots on greenish-gray bodies. They live near the soil surface in silken shelters covered with bits of grass. In spring, feeding usually stops by late May when larvae reach maturity and pupate. Moths then emerge to mate and lay eggs for the next generation.
Monitor lawns in June for buff colored moths flying low over the lawn and again in August. Seeing moths fly up while mowing or walking around the lawn does not confirm larvae will cause damage. The adult moths can fly considerable distances and may be coming from other infested areas.
If you suspect sod webworm but are unable to find the larvae or their frass, use a soap disclosing drench. Mix up two gallons of tap water with two tablespoons of liquid dishwashing detergent. Sprinkle this mix over one square yard of affected turf. Within a couple of minutes, the flesh-colored, spotted larvae will wriggle to the surface. If you find 10 to 15 larvae in a one square yard of turf, treatment is warranted.
Sod Webworm, http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/sodwebwm.htm
Sod Webworm Management in Lawns, http://ohioline.osu.edu/hyg-fact/2000/2011.html
7. Preen Organic with corn gluten meal is now available as an organic weed control option. It is a pre-emergence herbicide labeled for use in lawns, flower and vegetable gardens. As with all herbicides, read and follow label directions for application and apply the product at the correct time of the season.
Emerald Ash Borer (EAB) was recently confirmed 5 miles of the eastern Iowa border, near the LaCrosse, WI area. With it being that close to Iowa, questions about control are likely to increase in Nebraska. At this time, here is the recommendation of UNL Extension concerning EAB provided by Frederick P. Baxendale, Extension Entomologist and James A. Kalisch, Extension Associate. EAB Info, http://www.emeraldashborer.info/
Emerald Ash Borer Control Recommendations for Nebraska, May 2009
UNL Extension Entomology is not currently making specific recommendations for the control of Emerald Ash Borer (EAB) in Nebraska. Last year, a few garden centers prematurely promoted imidacloprid (Merit) for systemic protection against EAB. Because this pest is still a considerable distance away (western Wisconsin, western Illinois, and eastern Missouri), we believe this promotion was inappropriate and wasteful.
Our position continues to stress the importance of monitoring EAB activity in and around Nebraska. If and when infestations are confirmed nearby, say in western Iowa, we will immediately mobilize our publicity and educational campaign with news bulletins and articles on EAB and its management. At that time, Extension educators, state and local officials, nurserymen, and landscape professionals will be provided with the latest information on EAB biology, distribution, and management. For now, however, our focus remains on staying abreast of on-going EAB research in Michigan, Indiana, Ohio, and other states, and keeping the public informed on the status of EAB in the midwest.
9. Pine Sawflies have arrived. They are very small, and can be found clustered in the terminal growth of pines. You'll see an area of chewed-off needles, and below it, the black-headed insects. The easiest control is also the greenest: take a stick and lightly tap the branch, knocking the critters to the ground. Few if any will crawl back into the tree. If you'd rather use a chemical treatment, products containing permethrin (Eight), carbaryl (Sevin), insecticidal soap, or neem oil will work. The smaller the caterpillar, the easier they are to control.
Pine Sawfly, http://extensionhorticulture.unl.edu/Current/Sawfly.shtml
10. Bagworms will hatch in late May and early June. After the small bags, about one-fourth inch long, appear is a good time for control. Smaller insects are easier to control and applications in mid to late June will reduce or prevent feeding damage. Recommended insecticides include Bt (Bacillus thuringiensis), Spinosad, Permethrin, Carbaryl and Acephate.
11. Grass Control in Flower Beds- Perennial weedy grass, such as brome grass, are difficult to control in flower beds. Other than hand-pulling and mulching, the herbicides sold as Grass-Be-Gone or Over the Top can be applied post emergence to weedy grasses and provide decent control. Note these products contain a surfactant and it is not necessary to use a surfactant, commercial or dish soap, with these products as burning of desirable plants may occur.
12. Winter Dieback/Desiccation in Evergreens On conifers, continue to wait until June 1st to prune damaged tissue which may be brown, reddish or yellowish in color. Waiting allows new growth to fill in the damaged area. Pruning may remove leaf buds that will grow to repair damaged areas. When pruning evergreens, never prune back beyond where there is green growth or the plant will not regrow from this point.
Winter Desiccation Injury, http://extensionhorticulture.unl.edu/Current/WinterInjury.shtml
13. Transplanting Perennials- When to transplant perennial flowers is a common question. The rule of thumb is to transplant spring and early summer blooming perennials in fall, usually September; and transplant late summer and fall blooming perennials in spring just before or as new growth begins. Summer blooming perennials can be moved in either spring or fall. This is also the time when perennials should be divided.
14. Preen Application Weed Control Tip- When using Preen preemergence herbicide in gardens, season long weed control often will require multiple applications and the product must be watered in because it degrades in the sun.
15. Apple Twig Borers in Grapes: These borers have been found in grapes in Nebraska. Commercial and home grape growers should be aware of how to monitor for these borers. See information on the University of Nebraska Viticulture web site.
Grape Cane Borer, http://agronomy.unl.edu/viticulture/grape_cane_borer.htm