Using Biology to Time Post-Plant Management of Northern Root-knot NematodeBernadette Gagnier1, Michelle Moyer1, and Inga Zasada2

1Washington State University - Irrigated Agriculture Research and Extension Center, Prosser, WA USA2United States Department of Agriculture – Agricultural Research Service, Corvallis, OR USA

Results and ConclusionsIn Fall 2019 (Fig. 2), there were treatmentdifferences (p=0.03), where spring Salibroapplication had fewer RKN J2 than the fallNemacur application, However, treatmentswere not different from the untreatedcontrol.

Spring applications initially looked betterthan fall applications, but this was likelydue to the timing between application andfinal fall nematode sampling – they hadmore time to work. We are continuingevaluations in 2020 to get a clearer pictureof timing efficacy, as a minimum of 6months is likely needed to see full efficacy.

IntroductionThe northern root-knotnematode, Meloidogyne hapla(RKN) is a pest in winegrapes resulting in vinedecline, particularly in replantsituations. Currently, post-plant nematicide products areapplied at timings that wereestablished in California trials.By using a Washington-developed (East et. al, 2019)dynamic degree-day model ofsecond-stage juvenile (J2)RKN (East et al, 2019) (Fig.1), we may be able to improvethe efficacy of new post-plantnematicides.

MethodsThree different post-plant nematicides were evaluatedvia the cup method (Table 1) in a 4-year old commercialChardonnay vineyard in the Horse Heaven Hills AVA.Salibro (fluazaindolizine) and Nemacur (fosthiazate)target RKN J2 and were applied in the spring or fall.Nimitz (fluensulfone) targets RKN eggs, and wasapplied in the summer.

AcknowledgementsLiterature Cited / Additional ReferencesTo sign up for the V&E

newsletter visit:

East K.E, et al. 2019. Developmental Dynamics of Meloidogyne hapla in Washington Wine Grapes. Plant Disease 103:966-971.

Funding for this project has been provided by the Washington State Commission on Pesticide Registration,and the USDA National Institute of Food and Agriculture, Hatch project 1016563 . The authors would like tothank Kari Smasne, Dr. Julie Tarara and Melinda Garza of Ste. Michelle Wine Estates for their vineyardsupport. The authors would like to thank Dr. Charlotte Oliver, Dr. Katherine East, Margaret McCoy, AlexaMcDaniel and Maria Mireles for their technical assistance.

Aligning post-plant nematicide applications with nematode biology should increase product efficacy and reduce unnecessary chemical use.

Table 1. Nematicide products and timing. Salibro is not currently registered on grape, but will be. Nemacur is not a grape product, but is used for demonstration purposes.

Product Date of Application Predicted J2*Salibro Spring 24-April-2019 49.5%

Nemacur Spring 24-April-2019 49.5%

Nimitz Summer 23-July-2019 20.3%**

Salibro Fall 1-October-2019 59.1%

Nemacur Fall 1-October-2019 59.1%* As predicted using models in East et. al, 2019. ** Nematode J2 are expected to be low.

Fig. 1 - Soil degree day model of Meloidogyne hapla second-stage juveniles (J2). This model can be used to predict when J2 are present in the soil. Graph from East et. al, 2019.

Fig. 2 - Total Meloidogyne. hapla J2 per treatment at different sampling timepoints in 2019. Bars indicate standard error. Each treatment was replicated 4 times.

050

100150200250300350400

Control Salibro spring Salibro fall Nimitizsummer

Fosthiazatespring

Fosthiazatefall

J2 p

er 2

50 g

soi

l

Product Application Timing - 2019

Northern Root-knot NematodeIntial Summer Fall