Angelonia Flower Break Virus (AnFB) has been diagnosed on angelonia by serological testing by Agdia. This virus causes chlorotic mottling on the leaves and infected plants can also be stunted. This virus also causes streaking or breaking on the flower petals, from which it gets its name. No insects or mites have been reported to spread angelonia flower break virus. This virus can be transmitted in plant sap, and by the propagation of infected stock plants. It is not known to be seed transmitted. So far, it has been reported on angelonia, phlox, verbena and nemesia. There is no cure and virus infected plants should be discarded.

Photo

Leanne Pundt, University of Connecticut

Many growers will be potting up garden mums and it’s a good time to revisit your fertilizer program. Mums are heavy feeders during the first few weeks. After flowers are formed, nutrient demand diminishes. Your fertilizer program and fertilizer selection should be based on irrigation water quality, so have your irrigation water tested if it hasn’t been done and conduct regular soil tests to monitor soil fertility.

There are several ways to fertilize mums. Some growers use 100% water soluble fertilizer through a drip system, some use 100% controlled-release fertilizer and some use a combination of water soluble and controlled-release. To start plants off right and prevent premature buds:

Use moistened soil when potting up plants, then water-in freshly planted cuttings with a fertilizer solution containing 200 to 300 ppm of 20-20-20 immediately after planting. The cuttings will establish faster and grow more rapidly.

Do not stress the young plants during their first 4 to 5 weeks of growth, especially during the first 10 days of the crop. Keep plants moist, well fertilized and properly spaced.

 Check plant roots regularly to monitor plant health.

To encourage soft growth that branches freely, use 250-300 ppm 20-20-20 or a fertilizer that is at least 60% ammonical nitrogen as a constant feed during the first 2-3 weeks for all fertilizer programs. If using controlled-release fertilizer, keep in mind that its rate of release is affected by its formulation (rate of release), soil temperature and frequency of irrigation. Most formulations release at temperatures of 70°F or above, therefore during cold temperatures of late spring/early summer temperatures, fertilizer is going to be slow to release, when plants need the most fertilizer. This is why liquid feedings become important, to get plants moving and create vegetative growth. Liquid feeds of at least 60% ammonia forms of nitrogen, combined with no water stress, are important to minimize premature budding!

 Examples of Fertilizer Programs for Garden Mums

100% Water Soluble Fertilizer Using Drip Irrigation
After plants are established using 20-20-20 the first few weeks, switch to 200-250 ppm of 20-10-20 constant feed for 3-4 applications and then rotate to a calcium nitrate based fertilizer such as 15-0-15 for 1 application, then repeat. Once plants start to show color, reduce to 100 ppm constant feed.

Combination of Water Soluble Fertilizer and Low Rate of Controlled Release Fertilizer
Use 250 ppm of 20-20-20 at time of planting and constant feed for first two weeks  then change to 20-10-20, 300 ppm once per week and use clear water from first color until sale.

 More information is available from:

 Yoder 

 Garden Mums from Cell Packs

Tina Smith, University of Massachusetts

The following information was recently posted on the Massachusetts Introduced Pests Outreach Project website. This project is a collaboration between the Massachusetts Dept. of Agricultural Resources and the UMass Extension Agriculture and Landscape Program. Tina Smith

The fungus Gladiolus Rust (Uromyces transversalis) has been recently discovered on gladiolus plants in Minnesota. Until this past April, the only US records for this species were in California and Florida. The Minnesota record represents the most northern US location where the rust fungus has been found, by far.

Gladiolus rust remains a problem mainly for nurseries that grow gladiolus for sale as cut flowers. But if you grow gladiolus (or related tropical plants in the Iris family [Iridaceae], including Crocosmia, Tritonia and Watsonia species) or know someone who does, it is worth checking out the link at the bottom of the pest alert so you know what to look for in case you ever encounter this destructive pathogen.

 Jennifer Forman Orth
Massachusetts Introduced Pests Outreach Project
An educational component of the Cooperative Agricultural Pest Survey Program

Recent information posted on Gladiolus Rust

Whether spring plants are being moved outdoors to free up greenhouse space or displayed in outdoor retail yards, there are a few precautions to take at this time of year when temperatures can quickly dip from 80° to 25°.

Begin by choosing cool tolerant plants such as pansies, osteospermum, snapdragon, argyranthemum, petunias, verbena, bidens, calibrachoa, diascia, nemesia, annual phlox, alyssum and lobelia. Tropical and subtropical warm crops such as alternanthera, angelonia, New Guinea impatiens, lantana, vinca, celosia, cleome, coleus, cosmos, gomphrena, ipomoea, melampodium, portulaca, sunflowers, zinnias and many vegetables are naturally sensitive to cool temperatures and are not a good choice for early spring outdoor yards.

All plants, subjected to cold temperatures, should be acclimated or hardened off first. If taken directly from a warm greenhouse and not hardened off, even perennials and cool tolerant annuals will be injured by low temperatures.

To acclimate plants, lower the greenhouse temperatures to 45° – 55°F for several days or move plants to a cold frame for added protection. Monitor the weather forecast. As a guideline, avoid moving plants outdoors if a hard frost (colder than 28°F) is predicted at any point within at least three nights of when plants would be put outside and avoid moving plants on windy days. Use a minimum recording thermometers to monitor outdoor yards.

During mild weather, move the plants outdoors, and provide adequate space for good air movement. Avoid placing plants in low-lying areas where frost will more likely settle. Cold, dense air flows by gravity to the lowest areas where it collects.

Be prepared to cover plants with over-wintering thermo blanket such as polyethylene or polypropylene foam or move plants indoors if temperatures are expected to go below 28°F.

Without some sort of protection, you are always taking a chance when growing outdoors in early spring and occasionally plants will get damaged. By choosing cool tolerant plants, acclimating plants, closely watching weather forecasts and providing extra protection when needed, you can minimize risk, grow higher quality plants and provide an extra turn in production.

Tina Smith, University of Massachusetts

For more information see:

Moving Cool Tolerant Plants Outdoors: Risks and Benefits

Seasonal Outdoor Growing (by Four Star Greenhouse, Carleton, Michigan)

Spider mites may be introduced into your greenhouses on incoming plant material, or may move from weeds onto your crops. If hot spots of mite activity are detected early by regular scouting, biological control may be an option.

A fast acting predatory mite that is commercially available is Phytoseiulus persimilis. This predatory mite only feeds upon spider mites, and will disperse or starve with no prey. The adult P. persimilis is bright red in color, pear shaped, long-legged and slightly larger and more active than spider mites.

It is best released when mite populations are first noticed, in hot spots of mite activity. Relative humidity should be greater than 75% and temperatures above 68F for some hours of the day. (At low relative humidity (less than 60%), eggs shrivel and do not hatch.) Spider mite colonies should be reduced in two to three weeks.

The spider mite predator Neoseilus californicus is slower acting than P. persimilis, but can survive longer in the absence of prey. It is useful for keeping low spider mite populations under control. In certain situations where high temperature or relative humidity variations can occur, N. californicus may be an option. N. californicus is active at temperatures between 46°F to 95°F, 40-80% relative humidity. At low pest densities, it declines less than P. persmilis, for N. californicus can survive on other mites, thrips, molds and nectar. N. californicus can also be introduced preventively and is compatible with P. persimilis.

Some suppliers offer a mix of different species of predatory mites. Additional species are available that are adapted to outdoor use.

For more information see:
Biological Control of Two –Spotted Spider Mites

Leanne Pundt, Extension Educator, University of Connecticut

Downy mildew caused by species of Peronospora, Bremia, Plasmopara, and Basidiophora has become a serious problem in the ornamental industry. The pathogens are obligate parasites that infect certain species of ornamentals selectively. Symptoms occur as angular, chlorotic to necrotic spots on the upper leaf surface and a purplish, downy growth on undersides. Control depends on fungicide applications, the use of resistant cultivars, and cultural practices. Minimize periods of leaf wetness by reducing density of the plant canopy and avoiding overhead irrigation. High humidity, prolonged leaf wetness, and cool weather favor the development of Downy Mildew diseases. Once infection is established, sporangiophores emerge from the stomata on leaf undersides and sporangia are easily spread by splashing water, wind, or handling. Downy mildew fungi may reside in plant debris or weed hosts. Remove infected plants and weeds. Avoid prolonged periods of leaf wetness. Scout greenhouses regularly for symptoms of Downy Mildew and apply fungicides on a preventive basis in a regular spray program once the disease is detected. Fungicides registered for Downy Mildew include Alliette, Alude, Stature, Subdue Maxx, Heritage, and Compass O. Apply these chemicals in a tank mix with contact fungicides such as chlorothalonil, copper, or sulfur and rotate among chemical classes to prevent fungicide resistance development in the pathogen population.

Bess Dicklow, Plant Diagnostic Lab, University of Massachusetts

Photos: Argyranthemum, Rudbeckia, Veronica, Impatiens

Article with photos on Coleus: Mary Hausbeck, Michigan State