|EAST, K - Washington State University
|Schreiner, Roger - Paul
|MOYER, MICHELLE - Washington State University
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2018
Publication Date: 3/6/2019
Citation: East, K.E., Zasada, I.A., Schreiner, R.P., Moyer, M.M. 2019. Developmental dynamics of Meloidogyne hapla in Washington wine grapes. Plant Disease. 103(5):966-971. https://doi.org/10.1094/PDIS-07-18-1195-RE.
Interpretive Summary: Plant-parasitic nematodes, microscopic roundworms that feed on the roots of plants, are production-limiting pests in most wine grape producing regions of the world. In Washington state, the second largest wine grape producer in the U.S., plant-parasitic nematodes are found widespread in vineyards. However, wine grape growers do not have adequate methods to manage nematodes in this region. This research was conducted to characterize the development dynamics of an important nematode parasite of grape, the root-knot nematode, over a two-year period. It was discovered that the root-knot nematode produces only one generation per year in Washington wine grape vineyards. This result is significant because by gaining insight into the biology of a pest organism, it will be possible to better time management strategies. For example, it is now known that the susceptible stage of the nematodes is the most abundant in soil in the spring and fall. These findings will be used by wine grape growers to better time management strategies to reduce the impact of this production-limiting pest.
Technical Abstract: Meloidogyne hapla is the most prevalent plant-parasitic nematode found in Washington state wine grape vineyards. Understanding the developmental dynamics of M. hapla can improve the timing of management intervention. Three Vitis vinifera vineyards in Washington were sampled from March 2015 to March 2017 to determine the developmental dynamics of M. hapla by measuring the number of second-stage juveniles (J2) in soil, egg and adult female densities in roots, and fine root tips. A model of M. hapla J2 development based on soil growing degree days using a base temperature (Tb) of 0°C (GDDsoil) and a start date of 1 March was developed. This model was validated at two additional vineyards in Washington and was robust with R2 values for M. hapla J2 population increase > 0.74. Meloidogyne hapla has one generation per year and overwinters primarily as the J2 infective stage. Juvenile populations declined after 1 March reaching their lowest density around 1800 to 2400 GDDsoil (early July) and increased over the fall reaching a maximum density over the winter (October to March), from 4200 to 4800 GDDsoil. Meloidogyne hapla egg and root tip densities reached a maximum around 2800 to 3100 GDDsoil (early August). The number of females per root tip did not vary throughout the year. A single generation with defined peaks in M. hapla J2 population densities in Washington wine grape vineyards may allow for specific timing of management interventions to minimize the impact of this nematode on vine productivity.