Code:
OIV
452-1,
IPGRI
0,
IPGRI
Name: Leaf: degree of resistance to downy mildew (leaf disc test)
Description: The resistance of grapevine varieties to downy mildew (Plasmopara viticola) is to be observed under field trials over several years without the use of chemical plant protection and/or resistance inductors.
Observation during the whole vegetation period, as long as there are young leaves.
Because the zoospores penetrate through the stomata, the leaf discs have to be placed with the lower surface up.
Using a standardized spore suspension with 25,000 spores/ml (counting chamber), a pipette is used to place 40 µl
or 1,000 spores on each leaf disc.
Incubation: in complete darkness (aluminium coat), room temperature, 4 days.
Remark: if the inoculum remains on the leaf disc too long, lesions are produced. Therefore, 24 hours after inoculation, the spore suspension has to be removed by blotting with a filter paper.
The symptoms should be evaluated considering the climatic conditions, that could influence the evolution of the disease, and, possibly, on plants without any biotic or abiotic stresses.
Category:
,
GROUP OF CHARACTERISTICS,
ORGAN
Subcategory:
DOWNY MILDEW,
BIOTIC RESISTANCE - FUNGUS,
LEAF - MATURE,
LEAF - YOUNG
Code: OIV 452-1, IPGRI 0, IPGRI
Name: Leaf: degree of resistance to downy mildew (leaf disc test)
Description: The resistance of grapevine varieties to downy mildew (Plasmopara viticola) is to be observed under field trials over several years without the use of chemical plant protection and/or resistance inductors. Observation during the whole vegetation period, as long as there are young leaves. Because the zoospores penetrate through the stomata, the leaf discs have to be placed with the lower surface up. Using a standardized spore suspension with 25,000 spores/ml (counting chamber), a pipette is used to place 40 µl or 1,000 spores on each leaf disc. Incubation: in complete darkness (aluminium coat), room temperature, 4 days. Remark: if the inoculum remains on the leaf disc too long, lesions are produced. Therefore, 24 hours after inoculation, the spore suspension has to be removed by blotting with a filter paper. The symptoms should be evaluated considering the climatic conditions, that could influence the evolution of the disease, and, possibly, on plants without any biotic or abiotic stresses.
Category: , GROUP OF CHARACTERISTICS, ORGAN
Subcategory: DOWNY MILDEW, BIOTIC RESISTANCE - FUNGUS, LEAF - MATURE, LEAF - YOUNG