February 24, 2016

The bacterium Agrobacterium tumefaciens is a soil borne pathogen that causes crown gall on many types of plants. In greenhouse crops, Crown Gall has been diagnosed in recent years on mums, argyranthemum and osteospermum and this year it has been found in some of Selecta's lobelia production. Selecta found symptomatic plants in four varieties of Magadi Lobelia: Blue, Compact Dark Blue, White and Basket White. Selecta sent information out to their customers and is discontinuing shipments of Lobelia for this spring.

Topics: Diseases Content Type: Update
February 10, 2016

Treatments for fungus gnats are best directed against the larval stage. Many growers use beneficial nematodes Steinernema feltiae sold under the trade names of Nemashield, Nemasys, Entonem or Scanmask applied as a drench. Fungus gnat larvae are killed in one or two days by the symbiotic bacterium that dissolves their internal contents. 

Topics: Biological Control, Insects and Mites Content Type: Update
February 5, 2016

It has been an interesting winter. Given the warm temperatures this year, growers are advised to open up overwintering greenhouses on warm days to ventilate. Either roll up sides, open doors, use fans, depending on the type of overwintering greenhouse. Ventilating will lower the relative humidity. Greenhouses that are closed up will result in moisture buildup and encourage plant diseases to develop. Also, take time to inspect plants in overwintering houses, particularly for disease and injury caused by rodents.

Topics: Cultural Practices Content Type: Update
January 29, 2016

Small greenhouses (< 4,000 sq.) can be scouted as one unit. Larger greenhouses should be divided into 2,000 to 3,000 sq. ft. sections for ease of scouting. Scout propagation areas at least every 3 to 4 days. Use your prior experience to determine how many plants and which plants to inspect (those that are most susceptible to pests or diseases in your greenhouse). The more plants or locations inspected, the more likely it is that a problem will be detected in a timely manner, when treatments are the easiest.

Topics: Cultural Practices, Insects and Mites Content Type: Update
January 27, 2016

Teach employees to inspect incoming plants as they arrive and before plants are moved into production areas. Look for the presence of insects, mites, diseases, and cultural problems such as nutritional deficiencies. If feasible, quarantine infested or problematic plants in an isolated greenhouse or area so they can be treated before they are placed in production areas. Here are a few tips for inspecting incoming plants:

Topics: Insects and Mites Content Type: Update