Newspaper article The Florida Times Union

Nematodes Cause Variety of Problems; There Is No Quick Cure for These Tiny Pests, but You Do Have a Few Options

Newspaper article The Florida Times Union

Nematodes Cause Variety of Problems; There Is No Quick Cure for These Tiny Pests, but You Do Have a Few Options

Article excerpt

Byline: TERRY BRITE DELVALLE

Do plants wilt during the heat of the day, not respond to fertilizer applications and appear to be stunted? Nematodes may be lurking beneath the soil affecting the root system.

Nematodes thrive in Florida's sandy soil and mild climate and can be problematic on a wide host of plants, ranging from St. Augustine grass to tomatoes.

Some nematodes are beneficial, while others feed on plants and are called plant-parasitic nematodes. Nematodes are unsegmented worms that are microscopic in size, ranging from 1/100 to 1/8 of an inch in length. They have a very effective mouthpart that resembles a hypodermic needle used to puncture plants, inject digestive enzymes and feed on plant fluids.

Most plant-parasitic nematodes feed on plant roots and are divided into two types. One type remains in the soil while feeding (ectoparasitic), while the other type enters the plant, typically the roots (endoparasitic). The most common ectoparasitic nematodes include sting, awl, and stubby-root nematodes. Root-knot is the main endoparasitic nematode.

Symptoms: Both types damage the root system and limit the ability of the plant to take up nutrients and water. Affected plants may develop nutrient deficiencies, causing leaves to turn yellow. Plants will wilt, especially during the heat of the day, and may thin out by dropping leaves. Because of their inability to take up nutrients and water, they appear stunted. Also, while feeding, nematodes injure roots, allowing bacteria and fungi to enter the plant, sometimes causing root rots or vascular wilts.

So how do you determine if your plants are plagued with nematodes? If the entire lawn or plant bed is affected, nematodes are not the culprit. Typically nematode problems are localized, affecting a few plants at a time, and spread out a few feet each year.

It's easy to tell if root-knot nematodes are present because they inject hormones into the roots, causing noticeable galls on plant roots. Most vegetable gardeners who have grown tomatoes and okra are well aware of the symptoms. It's more difficult to identify damage from ectoparasitic nematodes that cause short stunted roots, necrotic spots on roots, and root rotting. Look for indicator plants that are found in lawns that have nematode damage such as spurge, sedge, and Florida pusley.

To determine if plants have nematodes and which nematodes are present, a nematode test is required. The cost is $20 for Florida residents and $25 for folks out of state. Nematode test kits are available at most County Extension offices or commercial clients may order kits from the assay lab in Gainesville (go to http://edis.ifas.ufl.edu/sr011).

Susceptible Plants: Although data is not available for all plants, there are certain plants known to have problems with nematodes. Boxwood, Buddleia spp., Hibiscus, Gardenia radicans, Bottlebrush, Pittosporum, Japanese Holly, Rose, Lantana, Ixora, and Acuba are all highly susceptible to root-knot nematodes. Bahiagrass is the most tolerant lawn but it can still fall prey if nematode numbers are high or drought conditions exist. …

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