Three of the treatments were of Actinovate, a biological fungicide that uses the bacteria, streptomyces lydicus to control nematodes. The three treatments were at 6, 12 and 18 ounces per acre.

Steddom also tested NI-9, an experimental biological control product not yet on the market, at various rates.  And he tested a mixture of Actinovate and NI-9.

For the test crop, he used pumpkins in raised beds, 40-inches wide and 6-inches high, under plastic mulching, a system comparable to what’s commonly used in commercial vegetable production.

All the treatments were applied through drip-irrigation tubing.  He harvested the pumpkins on Nov. 5 and compared yields as well as the extent of root galling.

Although Steddom did not find pumpkin yield differences among the various treatments, there were differences in the amount of visible galling on roots. Microscopic counts of root-knot nematode eggs per ounce of root were collected at another laboratory.

Surprising, in terms of eggs per ounce of root, the best control was achieved by Actinovate at the lowest rate of 6 ounces per acre, he said.

The root-gall index, which is largely a visible-eye rating, was also lowest with the 6-ounce rate of Actinovate. The 18-ounce rate of NI-9 achieved similar results.
“While yield was not impacted during this study, the reduction in reproduction rates has significant implications for future crops in this field,” Steddom wrote in his official report. “Neither phytotoxicity nor differences in plant vigor were observed at any time during this study.”

The other pleasant surprise is that Actinovate is by far more user-friendly than the standard fumigants. Though the fumigants rapidly degrade and pose no risk to the end user, Steddom said, they are dangerous to those who apply them. A private pesticide license is required to purchase and use the fumigants, but the biological control is available to homeowners without a license.

The study was funded by the U.S. Department of Agriculture’s IR-4 Project, which is also referred to as the Minor Crop Pest Management Program.

The full results of the root-knot nematode study will be available on the IR-4 website ( sometime in early 2011, he said.

 “Growers or homeowners wanting more information about root-knot nematodes and their control should contact their local county Extension agent,” Steddom said.

A county-by-county directory of AgriLife Extension agents can be found at