| Grape -- Young Vine Decline |
| Cause:
Young grapevine decline involves two distinct diseases: Cylindrocarpon black-foot disease, caused by Cylindrocarpon obtusisporum and by C. destructans, and young esca, caused by Phaeoacremonium inflatipes, Phaeomoniella chlamydospora, and ocasonally Phaeoacremonium aleophilum. Little is known about the etiology or epidemiology of these pathogens on young grapevines. These diseases affect grafted grapevines in the first 10 years of establishment and are not specific to any scion-rootstock combinations. Cylindrocarpon is soilborne and infects grapevines through natural openings or wounds on roots or other belowground portions of the rootstock such as the pith. Phaeoacremonium spp. are the pathogens responsible for Measles in older vines. It appears that these fungi are capable of living inside vines without producing symptoms, but have the ability to become severe pathogens as a result of poor cultural practices.
These root diseases have been found infrequently in the PNW. It is likely that these pathogens are and have been present for many years in PNW soils. The widespread planting of new vines and rootstocks during the 90's has increased awareness of these problems. In general, many other problems have been associated with declining vines including "J" rooted vines, root girdling, graft failure, crown gall, gopher damage, early fruit load and water stress. The later two conditions seem to favor both black foot disease and/or young vine decline. |
| Symptoms:
Young vine decline caused by either pathogen develops slowly in the first few seasons of vineyard establishment and production. Young vines generally appear normal at planting, but differences in vigor become marked by reduced caliper size of the trunk, shortened internodes, reduced foliage, and reduced leaf size. The first 3 to 5 years after planting, onset of foliar symptoms may appear as interveinal chlorosis, followed by necrosis and early defoliation. Viewing trunks of declining grapevines in cross-section, dark-brown to black streaking is evident in the vascular elements due to plugging of individual or aggregates of xylem vessels with amber to black gum (gummosis) and formation of tyloses. A few to most vascular elements may be discolored. Uneven wood maturity, usually associated with rapid desiccation, is another common symptom.
Below ground, symptoms include reduced total root biomass, reduced numbers of feeder roots, and sunken, necrotic root lesions. Symptoms of young vine decline resemble other important diseases of grape including uneven wood maturity as in Pierce's Disease, virus-induced incompatibility, esca or black measles, and some nutrient deficiencies. Black gumming in the vascular system is necessary for diagnosis of these diseases but never sufficient alone. Black or amber streaks in the vascular elements are deposits of phenolic compounds in response to wounding, a general plant defense mechanism. Physical injuries to the grapevine due to root tearing, disbudding, or other trauma during production or planting can result in phenolic depositions and black discoloration, or even outright death of tissue as the result of injury to cambium tissues. |
Cultural
control: Good management techniques which includes proper planting, irrigation, and fertility for young vines while avoiding devigorating stresses both before and after planting are very important for establishing a healthy and productive vineyard.
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References: Scheck, H., S. Vasquez, D. Fogle, and W.D. Gubler. 1998. Grape growers report losses to black-foot and grapevine decline. California Agriculture 52(4):19-23. |
| Content edited by: Jay W. Pscheidt on January 1, 2009 |
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