By Maegan Beatty
During the recent citrus insect management workshop at the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center, Larry Duncan, a nematology professor, discussed the sting nematode.
First recognized in the 1980s as a pest of young citrus trees, the sting nematode has adapted to coarse, sandy soils. The pest feeds at the root tip and causes stubby root symptoms. The sting nematode can thrive in a wide variety of hosts, including many weed species.
Integrated pest management (IPM) strategies that have been studied for the sting nematode include sanitation, rootstock resistance/tolerance, as well as cultural, chemical and biological controls.
A sanitation strategy, the Nematode Rootstock Certification Program, treats the citrus nematode, burrowing nematode and the coffee lesion nematode. However, this strategy is hard to use on the sting nematode considering its widespread damage.
In 1985, a survey of common citrus rootstocks found that all were infested and damaged by sting nematodes.
“There are a variety of ongoing trials taking place using experimental UF and USDA rootstocks,” Duncan said.
To date, some rootstocks in the trials appear more tolerant than others. These include UFR-1, UFR-5, Orange 14 and Orange 16.
A cultural IPM strategy for sting nematode is using non-host cover crops to suppress the pest. Duncan reported sunn hemp can suppress the pest prior to planting. Perennial peanut can suppress sting and dagger nematode in row middles, but it establishes slowly and requires initial irrigation, he added.
Chemical management includes the use of nematicides. Researchers tested six different nematicides to measure their effectiveness in treating citrus trees. Nematicide efficacy was variable, but oxamyl consistently reduced nematodes compared to the untreated trees.
“The fruit weight of the 4-year-old trees was significantly related to the size of the trees at the beginning of the trial and to the overall abundance of sting nematodes,” Duncan said, “However, the treatments did not increase yield enough to be profitable.”
The use of a combination of IPM strategies offers the best hope for future sting nematode control.
“Ideally, sting nematode will one day be managed in citrus with a combination of cover cropping with non-host plants, rootstock tolerance/resistance, HLB avoidance and judicious use of nematicides,” concluded Duncan.
For more information, see Duncan’s full presentation in video or PDF format.
Source: UF/IFAS
Maegan Beatty is a University of Florida student and AgNet Media intern.
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