Floriculture Greenhouse Update

Daylily Rust

Tuesday, 05 July 2005 08:59

Daylily rust (Puccinia hemerocallidis) was found on the daylily cultivar "Twice as Nice" in Massachusetts. Daylily rust was first detected in four states in the southeastern United States in 2000. As of June 2005, it was reported in a total of 28 states. In 2003 several cases were reported in Massachusetts and in 2004 one case of daylily rust was reported. Due to the limited number of cases of daylily rust in Massachusetts it is possible to limit the spread this disease in the state. If daylily rust is confirmed, growers will be required to follow quarantine procedures and treat infected plants with a fungicide or destroy infected plant material.

Growers are advised to inspect new stock coming into your nurseries or garden centers for symptoms of daylily rust. Raised orange-yellow to red-brown pustules will appear on both the upper and lower surfaces of the leaves infected with daylily rust. If you rub a tissue along the surface of the leaves, it will pick up the bright orange spores. An isolation period of at least 6 months is recommended to ensure the plants are free of daylily rust. The Massachusetts Department of Agricultural Resources is asking growers to report daylily rust via the MA Introduced Pests website (http://www.massnrc.org/pests/report.aspx) or via the plant pests and noxious weed hotline at 617-626-1779.

See the daylily rust fact sheet to view photos of daylily rust symptoms and for more information about this disease.

http://www.massnrc.org/pests/pestFAQsheets/daylilyrust.html

This pest alert is from the Massachusetts Introduced Pests Outreach Project, a collaborative project between the Massachusetts Department of Agricultural Resources and the UMass Extension Agriculture and Landscape Program aimed at preventing the establishment of new pathogens and pests in Massachusetts. Visit the project website (http://www.massnrc.org/pests) for more information on other emerging pests and to subscribe or unsubscribe from our pest alert list.

Julie Callahan, Massachusetts Department of Agricultural Resources

Slugs

Friday, 01 July 2005 09:37

Moist, rainy conditions are bringing out the slugs. Slugs feed actively at night, and injure plants by chewing ragged holes in leaves or stems. Feeding damage caused by slugs may be confused with damage caused by caterpillars, however caterpillars leave fecal droppings. Slugs leave shiny trails of dried slime. The slime helps protect their bodies from desiccation. After mating, adults lay round, clear eggs in clusters in damp locations. Slugs mature over several months to a year. Slug baits although messy, are probably the most effective tool for management. Baits containing metaldehyde (Deadline M-Ps, Deadline Bullets) work by stimulating water loss in slugs through excessive mucus secretion and through partial paralysis. The problem is when there is high humidity, the slugs do not dehydrate quickly enough and the poison may wear off before death. Metaldehyde baits may be more effective if days are sunny and warm, so that the slugs desiccate and then die. This bait is toxic to animals, so keep pets away. Bait containing methiocarb (Mesurol Pro) acts as a stomach poison and may be more effective under cool, wet conditions. Methiocarb (Mesurol 75-W) is also available as a wettable powder to be mixed with water and applied as a spray to protect plants. Iron phosphate (Sluggo) is another product available as slug bait. Slugs consume the iron, a heavy metal, which is toxic to them, become less mobile and begin to die within three to six days. According to the label, Sluggo can be used around pets and wildlife. A copper barrier can be used as an alternative to baits. Copper strips wrapped around greenhouse bench legs or placed on raised beds will act as a repelling barrier. The copper emits a small electrical charge that repels slugs.

Fact Sheet: Slugs and Snails

Tina

Broad Mites

Thursday, 23 June 2005 13:36

Tarsononemid mites including cyclamen mite and broad mite can cause serious damage to a wide range of greenhouse crops. Damage from broad mites appeared on New Guinea impatiens, garden impatiens and dahlias this week. Broad mites can also be a problem on African violet, ageratum, azalea, begonia, dahlia, gerbera, gloxinia, ivy, jasmine, impatiens, lantana, marigold, snapdragon, verbena, zinnia and vegetable plants. Broad mites inject a toxin from their saliva as they feed. Their toxic saliva causes twisted, hardened and distorted growth in the terminal of the plant and bronzed, rough lower surfaces. Young terminal buds can be killed and leaves turn downward. Broad mites are extremely small which makes them difficult to detect before severe feeding damage appears. Both broad mites and cyclamen mites are too small to be seen without the aid of a microscope. If characteristic symptoms are seen, send samples to a diagnostic laboratory that can inspect samples under a microscope.

Mites can be spread by workers' hands or on clothing. Infested hanging plants can infest plants below. If detected early, rogue infected plants as soon as possible. The following pesticides are registered for broad mites: abamectin (Avid), bifenthrin (Talstar Flowable, Talstar Nursery Flowable), chlorfenapyr (Pylon), dicofol (Kelthane), pyridaben (Sanmite), fenpyroximate (Akari). Repeat applications are usually necessary. The effects of their feeding may persist long after the mites have been eradicated.

Photos: Broad mite injury on peppers
Injury to New Guinea impatiens and garden impatiens

Fact Sheet: Managing Cyclamen Mites and Broad Mites in the Greenhouse

Information on sending samples to the UMass Plant Diagnostic Laboratory

Tina