6 PNL Volume 16 1984
Csizmadia, L. Research Station of Vegetable Crops Research Institute
Ujmajor, Hungary
Ascochyta pisi, a component of the Ascochyta disease complex,
frequently causes severe seedling losses in Hungary. To determine the
races present in Hungary, several isolates were obtained from diseased
plants collected in five different locations throughout the country.
To test for resistance to A. pisi, seeds were germinated for 3 days
at 10C and inoculated by dipping in a spore suspension containing
4-5 x 106 conidia per ml. Ten inoculated seeds were planted in a
15 cm pot filled with moist sand; then 20 ml of the inoculum were
sprayed on the surface of the sand. The pots were kept at 17°C with
16 hr diurnal illumination in a growth room. Disease ratings were made
ten days after inoculation and were based on the size and type of stem
lesions as follows:
1 - no stem reaction
2 - small (<1 mm) lesions only
3 - lesions 2-3 mm in length, no pycnidia
4 - deep necrotic lesions with pycnidia
5 - seedlings killed
Plants with ratings higher than 2 were considered susceptible.
Race identification was performed according to the methods of
Hubbeling (2). From Table 1, we can conclude that only race "C" was
present at the five locations.
Previous reports vary with respect to the proposed inheritance of
resistance of peas to A. pisi: two dominant genes (2); three dominant
genes (5); duplicate dominant genes (3); single gene with incomplete
dominance (1); single or 2-3 recessive genes (4).
Of nearly 200 varieties tested for resistance in the present study,
'Regis', 'Eldo', 'Rovar', and 'Venlona II' proved to be resistant.
Three susceptible varieties were crossed with Regis or Rovar and the F2
and BC generations were tested. In these crosses resistance to ract
"C" seems to be controlled by a single dominant gene (Table 2).
1. Cousin, R. 1974. Le pois. INRA, Versailles
2. Hubbeling, N. 1972. Proc. Eucarpia Conf. Peas 161-164.
3. Lyall, L. H. and V. R. Vallen. 1958. Canad. J. Plant Sci.
4. Matthews, P. and P. Dow. 1972. 63rd Ann. Rep. John Innes Inst.
5. Wark, D. C. 1950. Austr. J. Agric. Res. 1:382-390.
PNL Volume 16 1984