Potential efficiency of grapevine leafroll disease management strategies using simulation and real spatio-temporal disease infection data

Abstract

Background and Aims Grapevine leafroll disease (GLD) is one of the most widespread viral diseases of grapevine. In the present study, we suggest a methodology that combines real multiyear GLD spatial infection data and simulations of different management strategies to study their impact on GLD spread. Methods and Results We used real multiyear data on spatial infection of GLD to assess the infection risk to vines adjacent to infected vines. Directly adjacent vines were at significantly higher risk for infection in subsequent years than distant vines. Nevertheless, we found no difference in the absolute number of newly infected vines yearly between the directly adjacent and distant vines, indicating that GLD spread occurs in adjacent vines and randomly throughout the vineyard. We used the real multiyear GLD spatial infection data to simulate control strategies: uprooting; uprooting supplemented with insecticide treatment of neighbouring vines; and treatment of neighbouring vines with no uprooting and to study their impact on GLD spread. Uprooting with and without supplemental treatment to neighbouring vines significantly decelerated infection spread over a 7‐year period (from 30 to 8.6%). The combined treatment, however, of infected and neighbouring vines yielded a lower infection level with less uprooting events compared with uprooting alone. Conclusion Despite the risk of GLD spread to distant vines, the significantly higher risk of directly adjacent vines and their known location make them more relevant to management strategies for the control of disease dissemination. Significance of the Study The combination of simulations with real data revealed additional information on GLD spread under different management strategies that deviated from the expected dissemination process.

Influence of mating disruption on the reproductive biology of the vine mealybug,Planococcus ficus(Hemiptera: Pseudococcidae), under field conditions

“…Complementary insecticide applications in mating disruption trials in commercial vineyards are sometimes unavoidable in order to control other primary pests (e.g. the European grapevine moth), reduce the spread of GLRaV, and prevent severe crop damage …”

Grapevine Leafroll: A Complex Viral Disease Affecting a High-Value Fruit Crop

“…In general, the spatio-temporal spread dynamics over multiple years indicates two common patterns of secondary spread (28,148). One is aggregation or clustering of infected vines, suggestive of virus spread between adjacent vines within a row and across adjacent rows as a consequence of vine-tovine movement of mealybugs around the primary foci of infection.…”

“…Roguing or removal of infected vines is one such strategy recommended to effectively slow disease spread while ensuring profitable grape production (10,148). Although symptom-based roguing can be implemented in red-berried cultivars, caution should be exercised while practicing this strategy for GLD management in whiteberried cultivars, since they express no visual symptoms.…”

“…As a precaution, removal of at least one adjacent vine on either side of GLD-affected vines in a given row is recommended to reduce possible risk of residual inoculum present in the vineyard. A recent study in Israel showed that roguing infected vines can significantly reduce the rate of GLD spread from 30 to 8.6% over a 7-year period (148). Roguing was also shown to be economically viable if disease prevalence is less than 25% in Cabernet franc vineyards in New York (10).…”

Does mating disruption of Planococcus ficus and Lobesia botrana affect the diversity, abundance and composition of natural enemies in Israeli vineyards?

“…One of the pests, the vine mealybug Planococcus ficus (Hemiptera: Pseudococcidae), damages grapes by secreting honeydew that attracts molds, and by feeding on leaves and fruit. It also acts as a vector of viral diseases of grapevines . The second pest, the European grapevine moth Lobesia botrana (Lepidoptera: Tortricidae), causes direct economic damage by feeding on the plant, and indirect damage by increasing the susceptibility of the berries to gray mold, Botrytis cinerea (Pers) .…”