ISHS Acta Horticulturae 473: International Symposium on the Importance of Varieties and Clones in the production of Quality Wine
GRAPE PHYLLOXERA - GRAPE VARIETIES - GRAPE IPM |
| Authors: | J. Granett, L. Kocsis, Amir D. Omer, M. Andrew Walker, D. Lotter |
| Keywords: | Vitis vinifera, Daktulosphaira vitifoliae, Integrated Pest Management, rootstocks |
| Abstract:
One hundred and thirty years ago the grape phylloxera Daktulosphaira vitifoliae (Fitch) (Homoptera: Phylloxeridae) became the most dangerous pest of grapevines, damaging vineyards initially in Europe and then world-wide. It occurs in almost every major viticultural region. The pest has been controlled for a century by use of American Vitis rootstocks and this use has become one of the most successful case histories of host plant resistance. However, phylloxera is genetically variable in its ability to use hosts and it is likely that natural population constraints differ amongst its widely spread habitats. If we would like to see past successes with host plant resistance continue, we have to be aware of these variations and take actions to limit their potential for destruction. In this paper we will present laboratory bioassay data substantiating phylloxera variability and discuss the risk to field plantings. Next, we will demonstrate the existence of other natural controls on phylloxera population growth. Finally, we will suggest a course of research, which will give us the tools to continue using rootstocks for another century. Bioassays were conducted in the laboratory on phylloxera strains from California and Hungary against five rootstocks (AXR#1 [Ganzin 1], 41B, Riparia Gloire, 5C and SO4) and the European grape, Vitis vinifera cultivar Cabernet Sauvignon. Experiments were conducted both on field-grown 2-year-old root sections and on sterilized tissue culture plantlets. California biotype A is able to survive, develop and reproduce on Cabernet Sauvignon but survives and develops poorly on the rootstocks. California biotype B is similar to biotype A except for its strong capacity on AXR#1. However, the six Hungarian strains tested are able to survive, mature and reproduce on Cabernet Sauvignon and each of the rootstocks with the exception of Hung-1G, which was not competent on Cabernet Sauvignon. We have not confirmed field damage by the Hungarian phylloxera to these particular rootstocks. These data demonstrate that under laboratory conditions, 1) there is considerable variation in phylloxera's ability to use rootstocks that in some locations have high resistance 2) the potential for loss of resistance is not necessarily limited to rootstocks that have some V. vinifera parentage. Sampling California grape roots over two years showed that populations reach a peak midsummer, decline after midsummer, have a second peak with the fall root flush, decline to minuscule levels in winter, and overwinter as first instars. The decline after midsummer was due to unknown nutritional or mortality factors that could be related to root availability, root physiology or soil ecology. The decline of the second population peak was correlated with cooling temperatures. We hypothesize that vineyard conditions may be manipulated to minimize phylloxera populations and damage. We suggest that an integrated pest management program for phylloxera will decrease the likelihood of biotypes developing and the damage they inflict on vineyards. | |
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