In the fall of 2010, garlic bulbs potentially infested with the garlic bloat nematode, Ditylenchus dispsaci, were exported from Canada into New York as a food product. However, following arrival in New York, they were distributed as seed garlic. They were then shipped throughout the northeast for production purposes. In New Hampshire, it is known that this garlic was distributed to the following zip codes: 03221, 03303, 03833, and 03070. No further information regarding distributors, size of shipments, etc., has been provided at this time. This nematode, which is also known as a bulb and stem nematode, causes bloated, twisted, swollen leaves, and distorted and cracked bulbs with dark rings. Infestation with this nematode can weaken plants, causing them to be susceptible to secondary infections. Presence of this pest can affect export of the infested crop. Besides being a concern in garlic, this nematode can also affect other Allium species, such as leeks, onions, and chives, as well as other crops and plants including flower bulb crops, iris and gladiolus, and nightshades. The nematode can overwinter in the soil, and can be moved throughout the field on farming equipment, shoes, etc. Management recommendations include destruction of dry plant debris which can harbor the nematode, management of nightshade near crops, crop rotation away from Allium species on a four year cycle, good sanitation practices, use of bio-fumigant cover crops, and chemical fumigants.
You can submit plant samples for nematode identification to the University of New Hampshire Plant Diagnostic Lab, for a fee of $20 per sample. UNH Cooperative Extension Plant Pathologist Cheryl Smith asks growers to please call her at 603-862-3841 for sampling instructions and to let her know they are sending samples. Samples should be either brought in or shipped overnight via Fed Ex or UPS. The PDF of the lab sample form, is also available on the website.
Click on the following links to find out more information about the garlic stem and bulb nematode.