Greenhouse Update - August 11, 2006
Leanne Pundt, Extension Educator, University of Connecticut
The extended hot and humid weather last week took its toll on workers as well as plants. Warm temperatures speeded up insect and mite development and promoted Pythium root rot diseases.
Garden Mums -- suffered from root decline due to numerous causes. Over watering was frequently to blame, especially less vigorous varieties on drip irrigation or plants in low, poorly drained areas in the field. Examine roots and growing media. Roots should be healthy and white. Symptoms of Pythium root rot include dark brown and mushy roots with a rattail appearance. Yellow or dull green foliage resembling a nitrogen deficiency is often the first symptom grower's notice. Fungicide drenches such as Banrot, Truban, Alude, Banol or Subdue Maxx can be used according to label directions. (However, isolates may be insensitive to Subdue Maxx). Avoid stresses to the root system -- either over-or under-watering; both injure the roots, predisposing them to fungal attack or high salts.
Various caterpillars can become occasional pests of garden mums, too.
Variegated Cutworms -- are a type of climbing cutworm that can chew holes in the foliage of a wide range of plants including vegetables, such as lettuce and tomatoes, fruit crops, field crops and turf. On garden mums, they tend to chew off the smallest branches. Larvae tend to feed primarily at night but may occasionally be active during the day. Like other cutworms, they crawl into a ball when disturbed. Variegated cutworms overwinter as a pupa in the soil. It takes about 6 to 8 weeks for them to complete their life cycle. In the northern U.S., there may be 2 generations per year. Spinosad (Conserve) is labeled for use against cutworms.
Variegated Cutworm Larva
photo: Lacy L. Hyche, Auburn University,
www.insectimages.org
click for a larger image
European Corn Borers -- may tunnel into the stems of garden mums, cut flowers and perennials such as Shasta daisies. For the latest trap captures, by the UConn IPM Program, see the Vegetable Pest Message on this site. Go to the July 10th message on the NE Greenhouse Web Site for more information on European Corn Borers.
Inspect incoming poinsettia cuttings for fungus gnat larvae -- look for blunt root tips, or the presence of unrooted cuttings among a strip of rooted cuttings. The black-headed fungus gnat larvae may also be seen. Apply an insecticide drench as soon as possible after transplanting. Many of the insect growth regulators including Citation (often best used early when soil contact is easily obtained), or Ornazin can be used. If using the IGR Distance against fungus gnats, be sure to follow all label use precautions for poinsettias to avoid leaf malformation. DuraGuard, which works by contact, is labeled for both fungus gnats and shore fly larvae. Gnatrol, is most effective against the young, first instar larvae. Repeated applications at high rates are often needed. The neonicotinoids – Safari, Celero, Flagship, Marathon, Tristar are labeled for use against fungus gnats. (Do not rotate with other pesticides in Group 4a).
If you would like to receive an email notice when new greenhouse updates are posted on the website, please email me at: leanne.pundt@uconn.edu . This will be an undisclosed list, and your email address will remain private.
| New England Greenhouse Update now online. University Extension Specialists in New England, in conjunction with USDA's Northeast Sustainable Agriculture Research and Education, contribute information to this new website. Timely updates are provided for commercial growers of greenhouse crops and flowers in Massachusetts, Connecticut and Rhode Island. You can use this additional resource for more information about current observations and recommendations on environmentally safe production practices. |
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GREENHOUSE IPM COORDINATOR (commercial interests and growers) |
LEANNE PUNDT | 860-626-6240 |
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