SUSCEPTIBILITY OF 32 WALNUT VARIETIES TO GNOMONIA LEPTOSTYLA AND XANTHOMONAS CAMPESTRIS PV JUGLANDIS
To detect the level of Gnomonia leptostyla infection, 100 leaves per variety were sampled at random on 35 limbs. The number of necrosis with acervuli was determined and data were analyzed with a multiple range test (with conf. int. of 95%).
Incidence of Xanthomonas juglandis was estimated as percentage of leaves infected with the bacteria. The necrosis with the diameter smaller than 3 mm were analyzed by a light microscope.
The 32 accessions were included in 5 different classes of susceptibility to G. leptostyla depending on the number of necrosis with acervuli. The fungus did not infected Hartley (A) and Mayette (F), while J. Jefe (S) and VZ5 (S) are the most susceptible.
During vegetative season one quarter of the 32 accessions showed the bacterial presence on the 20% of the necrosis analyzed.
In October, Payne (A), Xerta 119 (S), Xerta 122 (S), VZ4 (S), VZ5 (S) and FK5 (G) and TR8 (I) showed the highest percentage of infection of X. juglandis.
In the 1995 we will continue this research to confirm these preliminary data.