|
A Technical Guide for Wine Producers
|
|
RECENT ARTICLES | WYNBOER HOME
Integrated vine mealybug (Planococcus ficus) control with the use of pheromone trapping in South African vineyards
Introduction
Vine mealybug, Planococcus ficus Signoret, is one of the key pests in South African vineyards causing economic damage to infested vineyards. Sooty mold grows on honeydew excreted by mealybugs and renders fruit unmarketable. Small populations of P. ficus can also cause economic losses due to large quantities of honeydew excreted (Bentley et al. 2002). Vine mealybugs vector viral diseases of grapevines (Rosciglione & Gugerli 1989, Tanne et al. 1989, Engelbrecht & Kasdorf 1990, Golino et al. 1999, Sforza et al. 2000) and South African producers are encouraged to control P. ficus populations in order to limit the transfer of these diseases. The low tolerance for P. ficus populations in vineyards therefore necessitates the use of a sensitive species-specific monitoring method for vine mealybug. Current monitoring methods consist of time consuming examination of plant material for the presence of mealybugs (Geiger & Daane 2001, Walton 2003). This method of monitoring is, however, accurate and is coupled to action thresholds (Walton 2003). Pheromone baits have been developed (Millar et al. 2002) and is used to monitor the presence of P. ficus pest populations in Californian vineyards. Pheromone baits attract adult male vine mealybugs (Fig. 1) which form approximately 50% of the total mealybug population in colonies in vineyards (Kriegler 1954).
This method of monitoring was further shown to be extremely sensitive in detecting low P. ficus field infestations and could serve as a useful detection tool for P. ficus pest populations in South African vineyards (Millar et al. 2002). The object of this article is to demonstrate the potential use of pheromone monitoring in combination with physical stem monitoring in an integrated P. ficus management system in South African vineyards.
Pheromone trapping protocol
Pheromone lures:
Traps and trapping frequency:
Results of counts can be e-mailed to the client in a period of five working days. Traps need to be changed on a biweekly basis, but only when vine mealybug males are caught. If no vine mealybug males are found on the sticky pads, they can be left in the traps until the next sticky pad change are scheduled.
Biweekly pheromone trapping should start in October and continue until harvest. Pheromone trapping could continue on a monthly basis after this period in commercial blocks with a history of high infestations. Out-of-season pheromone trapping should, however, continue throughout the year in blocks with a history of high vine mealybug infestation, as well as blocks where there is no tolerance for P. ficus infestations (propagation and quarantine vineyard units).
In-vine and block placement
Traps can be hung at or above the cordon (Fig. 3) and the trellis wires can be used for attachment (Daane 2003). The traps can be placed in the canopy for protection against the wind and sun. Daane (2003) suggested that the open ends should be exposed so that vine mealybug males can easily fly into the triangular center of the yellow delta trap. It was found in studies in South Africa that the pheromone lures are very attractive up to a distance of 50 m away from a mealybug source.
It is therefore suggested that traps are in blocks each more or less 1 ha in size.
Adult vine mealybug males were caught in pheromone traps up to a distance of 100 m away from the source of mealybugs. These catches were, however, low compared to the trap count 25 and 50 m away from the mealybug source. No males were caught at 200 m away from the source on any of the sampling dates. This suggests that traps placed at the rate of 1/ha in commercial vineyards could attract and catch P. ficus males from adjacent blocks. This could impact on trap counts, especially if adjacent blocks have high P. ficus infestation levels, which may result in a misperception of the actual infestation levels in that specific block. For this reason physical stem counts should be done for verification of actual P. ficus infestation levels (Walton 2003).
It is further recommended that traps are placed in areas where human movement takes place at regular intervals such as near roads, end rows and packsheds. Old vineyards are often a source of new mealybug infestations. New vineyards planted on soil where old established vineyards were taken out, can also be areas where new mealybug infestations could occur and should be monitored with these traps (Walton 2003).
Correlation between pheromone trap counts and vineyard infestation
There was a clear correlation between pheromone trap counts and percentage stem infestation. Work indicated that the action threshold of 2% P. ficus stem infestation (Walton 2003) will be reached at an adult male vine mealybug pheromone trap count of above 65 per biweekly trap count. During both seasons pheromone traps caught adult males before any physical signs of P. ficus infestation could be found. This suggests that pheromone traps are more sensitive in detecting the development of P. ficus populations in specific vineyards than physical monitoring of stems and can be an extremely useful detection tool in quarantine situations.
Physical P. ficus stem monitoring
As mentioned above, it is important to verify high pheromone trap counts with physical P. ficus stem counts in order to prevent overreaction due to perceived 'high infestations'. The only reliable monitoring method which has action thresholds attached to it is physical stem monitoring for mealybug populations.
Conclusions
Vine mealybug pheromone traps are a new tool which can be used to aid the integrated management of P. ficus, one of the key pests in South African vineyards. These traps are extremely sensitive in detecting low populations of P. ficus in vineyards. This characteristic can be profitably used as a quarantine and early warning tool for P. ficus pest populations in vineyards. Work in South African vineyards indicated that these traps can be used to direct physical stem monitoring to problem areas. This will lead to physical P. ficus monitoring being less labor intensive and therefore more easily implemented in commercial vineyards. It is stressed that physical stem monitoring of vines should follow as a verification tool in blocks where sufficiently high P. ficus male counts were found. Physical monitoring is, however, necessary before control actions such as chemical sprays or mass releases of the natural enemy Coccidoxenoides peregrinus (Walton 2003) can follow.
The Pest Management Division at ARC Infruitec-Nietvoorbij can be contacted at Tel. 021 809 3458 if further information is required.
References
Bentley, W. J., Cone, W. W., Daane, K. M. & Korfanta, N. M., 2002. Mealybugs in North American vineyards. In L. T. Wilson, and T. J. Dennehy (eds.), Vineyard Pest Management (in press). Pergammon, Oxford, UK. |
|
Wynboer is incorporated in WineLand, magazine of the SA wine producers.
Visit our sister sites:
|
V. M. Walton, ARC Infruitec-Nietvoorbij
Fig. 1. An adult male vine mealybug.
Fig. 2. The adult male vine mealybug (arrow a), has located the female by means of a pheromone plume secreted by the sexually mature female mealybug (arrow b).
Fig. 3. Position of yellow delta sticky trap with Planococcus ficus (vine mealybug) pheromone lure.
| UP |
COPYRIGHT (C) 2000 WineLand |