Broad mites and Cyclamen mites
Wednesday, 07 July 2010 13:51
Damage from broad mites has been reported on peppers and New Guinea impatiens. Tarsononemid mites including cyclamen mite and broad mite can cause serious damage to a wide range of greenhouse crops such as New Guinea impatiens, garden impatiens, dahlias, gerbera, ivy, lantana, snapdragon, verbena, zinnia, peppers and other vegetable plants. Broad mites inject a toxin from their saliva as they feed. Their feeding 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 and cyclamen mites are too small to see without the aid of a microscope. Regular inspection of crops for their feeding damage is the best way to detect infestations. If characteristic symptoms are seen, send samples to the diagnostic laboratory where they can be inspected under a microscope.
Mites can be easily spread to healthy plants by workers' and infested hanging plants can infest plants below. During scouting and other tasks, enter mite-infested areas last. Clean the greenhouse thoroughly.
Damage caused by cyclamen mites has been observed on Delphinium. Symptoms are very characteristic and are sometimes mistaken for disease. Leaves cup or curl and are often blackened. Flower spikes are stunted and blackened. Aconitum, dahlia, chrysanthemum, verbena and viola are also hosts, although they do not exhibit so serious a reaction to the feeding.
Miticides labeled for broad mites and cyclamen mites on ornamentals include: products containing abamectin (Avid, Lucid, Minx and others), chlorfenapyr (Pylon), dicofol (Kelthane), fenpyroximate (Akari) and spiromesifen (Judo). Note that the effects of their feeding may persist long after the mites have been eradicated. The Judo (spiromesifen) label recommends not spraying impatiens spp. (including New Guineas). Follow label precautions for crop safety. It is an very effective spray against broad mites. For vegetable plants see labels of Pylon and Minx.
Fact Sheet: Managing Cyclamen Mites and Broad Mites in Greenhouses
Tina Smith, University of Massachusetts and Leanne Pundt, University of Connecticut
Wilting Mums
Tuesday, 06 July 2010 12:28
Fall mums will exhibit signs of wilting during extended periods of 90 plus degree temperatures. The solution may not be as easy as turning on the irrigation.
Fall mums wilt when the soil is dry, but wilting will also occur in hot weather which may cause plants to be stressed, or if the roots are damage from a root disease such as Pythium, even if the soil is saturated with water. When the roots stop functioning normally the plants will show signs of stress by wilting.
Keep in mind fall mums can survive excess amounts of fertilizer and resulting soluble salts when temperatures are normal and soil moisture is maintained. Problems occur when the growing medium is dry and the salts become more concentrated, resulting in root damage. The plants will react first by wilting and than collapsing.
Take precautions to avoid overwater garden mums especially during periods of hot weather like this week. Lift the pots and check the roots periodically. If the pots feel heavy and the soil is saturated, do not irrigate, even if it is hot. However, do not allow plants to dry to wilt prior to watering.
If plants are wilting on a regular basis and excess amounts of fertilizer have been used, the roots maybe damaged and root disease will occur. Check the plant roots, especially with slower growing varieties. The roots tell a lot about a plants health, often before the top growth shows symptoms.
Paul Lopes, Tina Smith
University of Massachusetts Extension
Potato Leafhopper
Tuesday, 06 July 2010 08:26
Watch for potato leafhoppers. Leafhoppers are found on many different out-door grown perennials, vegetables and sometimes garden mums. Of the many species of leafhoppers, the potato leafhopper and aster leafhopper are most likely pests on ornamentals in
The potato leafhopper feeds by inserting a needle-like beak into the plant and sucking out the sap. It also injects a toxin as it feeds so leaves may develop a v-shaped brown, edge burn at the tip known as "hopperburn". Photo: hopperburn on Astilbe. This injury may be confused with leaf scorch especially on drought-sensitive Astilbe. Plants may also be stunted with distorted new growth. Growers with retail customers should be aware that potato leafhoppers are building up in beans, potatoes and eggplants now. Damage is worse under drought conditions.
The aster leafhopper transmits the pathogen that causes aster yellows. Other species of leafhoppers may not inject a toxin or transmit diseases as they feed so control may not always be necessary.
Scouting: Brush the leaves of plants with your hand. Small light yellow-green potato leafhoppers dart around and fly up from foliage when disturbed. Tap the foliage over a yellow sticky card or briefly place a sticky card among the plants to catch adults. Potato leafhoppers (Empoasca fabae) adults are approximately 1/8 inch long, and light green with characteristic 6 white spots just behind their head. Once you see adults, look closely at several leaves for nymphs. Nymphs are small, narrow light green wedge shaped insects that move very fast sideways, front and back. Look on the underside of leaves along the leaf vein for the young nymphs especially on Alcea, Astilbe and Dahlia.
Management: The potato leafhopper does not overwinter in
Systemic insecticides such as neonicotinoids may be applied to prevent feeding damage when leafhoppers first appear. There are many other pesticides labeled for leafhoppers including azadirachtin, (MOA Group 18) pyrethroids (MOA Group 3), and Beauvaria bassiana(MOA Group M). Pesticides with limited residual will need to be reapplied with good coverage on the undersides of leaves. See the New England Guide for specific pesticides.
Fact Sheet: Leafhopper Pests of Connecticut Nurseries and Landscapes
Leanne Pundt, University of Connecticut
Tina Smith, University of Massachusetts
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