Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2010
Publication Date: 10/1/2011
Citation: Zasada, I.A., Walters, T.W., Pinkerton, J. 2011. Post-Plant nematicides for the control of root lesion nematode in red raspberry. HortTechnology. 20:856-862. Interpretive Summary: Plant-parasitic nematodes are microscopic soil worms that attack raspberry plants and cause significant loss in yield to this crop annually. Raspberry farmers face an enormous problem because they lack effective ways of reducing the numbers of nematodes in soil after a raspberry crop has been planted. This research was conducted to identify nematicides that can reduce root lesion nematode numbers, an important parasite of red raspberry. A range of nematicides, including plant-derived products and new chemistries, were tested against the root lesion nematode in soil only and plant-based experiments. Several of the nematicides reduced nematode survival in soil only tests, including the nematicides Nema-Q, 1,3-dichloropropene, oxamyl, fosthiazate and methomyl. When the nematicides were screened against nematodes in plant-based experiments, only oxamyl and fosthiazate reduced root lesion nematode numbers. These results are significant because they will help guide the selection of products for root lesion nematode control in raspberry. This research will be by used scientists and farmers to manage root lesion nematode in established raspberry fields.
Technical Abstract: There are currently few registered post-plant nematicides available to control root lesion nematode (Pratylenchus penetrans, RLN) in red raspberry (Rubus ideaus). The rate of raspberry decline due to RLN depends upon the nematode population density but usually occurs over a 3- to 4-year period. To identify a post-plant nematicide to control RLN in red raspberry, a number of nematicides were tested in both soil only and plant-based experiments. In soil only experiments, soil naturally infested with RLN was drenched with the nematicides and nematode survival assessed 7 and 14 days after treatment. Fosthiazate and oxamyl reduced RLN recovery 92% and 52% across trials and sampling times, respectively, compared to the nontreated control. Other nematicides that resulted in moderate, and sometimes inconsistent, control of RLN were Nema-Q® (10,000 PPM), 1,3-dichloropropene (600 PPM) and methomyl. In plant-based experiments red raspberry ‘Meeker’ was established in pots, inoculated with soil infested with RLN blended with greenhouse soil, and the nematicides were either applied as soil drenches or as a foliar application. Nematode reproduction and cane and root weight were quantified as measurements of nematicide toxicity and phytotoxicity, respectively. Similar to soil only experiments, fosthiazate and oxamyl were the most effective in reducing RLN population densities in established red raspberry; fosthiazate and oxamyl significantly reduced RLN/g dry root population densities by 97% and 87%, respectively, compared to the infested, nontreated control. None of the other nematicides reduced RLN population densities compared to the infested, nontreated controls. There was no phytotoxicity to red raspberry associated with any of the nematicides. Due to the uncertainty associated with the registration of fosthiazate and/or oxamyl for use in red raspberry, these results demonstrate that this industry is still searching for a post-plant nematode management practice to control RLN.