SUSCEPTIBILITY OF SOME WALNUT CULTIVARS TO GNOMONIA LEPTOSTILA (FR.) CES. ET DE NOT.

The aim of the present research was to study and compare the susceptibility of 15 walnut cultivars – 5 Bulgarian (B), 3 French (F), 2 Hungarian (H), 2 Italian (I) and 3 American (A) – to Gnomonia leptostyla (Fr.), the pathogen causing leaf spot.
The study was conducted under natural environmental conditions in a seven year-old walnut collection orchard of the Fruit Growing Institute, Plovdiv, during the period 2005-2007. The evaluation of the attack produced by this pathogen was carried out on different organs (leaves and petioles) in two periods of the year (June and October). Plant material was collected from 5 trees of each cultivar from the walnut collection.
To detect the level of G. leptostyla infection, 100 leaves of 5 limbs were randomly collected from each cultivar.
The number of necrosis with acervuli was detected and data were analyzed by a multiple range test (with conf. int. of 95%). The studied cultivars were divided in classes of susceptibility to G. leptostyla depending on the leaf infestation index, by McKinney.
None on the investigated cultivars demonstrated complete resistance.
Out of the 15 studied walnut cultivars one was resistant (‘Chandler’(A)), 5 cultivars were slightly susceptible (‘Fernor’ (F), ‘Tiszacsecsi’ (H), ‘Fernette’ (F), ‘Silistrenski’ (B) and ‘Milotai’ (H)), 4 cultivars were susceptible (‘Kuklenski’ (B), ‘Hartley’(A), ‘Sorento’(I) and ‘Lara’ (F)), 3 cultivars were highly susceptible (‘Sheinovo’(B), ‘Izvor 10’ (B) and ‘Slivenski’ (B)) and 2 cultivars were very highly susceptible (‘Alososzentivani’ (I) and ‘Seer’ (A)). Intensity of the disease attack ranged from 4.9% (‘Chandler’) to 62.4% (‘Alsoszentivani’).

I Balkan Symposium on Fruit Growing

V.A. Arnaudov, S.I. Gandev

Juglans regia, cultivars, Marsonina juglandis, infection

https://doi.org/10.17660/ActaHortic.2009.825.64