Control químico de la roña del manzano Venturia inaequalis (CKE) WINT en el ejido Rancho Nuevo, Arteaga, Coahuila.

Abstract

The apple explotation (Malus domestica Borkh), in the region of the Sierra of Arteaga, represents the larger source of employment and inputs for the habi- tants, of the region; during the last five years the production of apples in the municipe has increased notable obtaining a average production of more than 42 thousand tons, per year. 

The presence of the disease known as apple scab Venturia inaequalis, has increased to such a grade that 30% of the production has been afected; accor- ding with the last part, the present investigation has as a main objective evaluate differents fungicides for the control of V. inaequalis and to reduce the number of applications during the cicle of production of the tree fruit. During the productive cicle of 1990 it was utilized the variety Golden Delicious, selecting 24 trees, es- tablishing a aleatory block desing with 6 treatments and 4 repetitions, the treat- ments were: 1) Myclobutanil (Rally 40 W 1.5g); 2) Myclobutanil (Rally 40 W 0.75 g + Mancozeb (Dithane M- 45, 20 g); 3) Difenoconazole (Score 1.5 cc); 4) Dife- noconazole (Score 1.0 cc) + (Flonex Z 400 20cc); 5) Zineb (Flonex Z 400 40cc) y 6) Testigo. The dose were mixed in 20 I of water and 2 cc of adherent and Bio- nex dispersant for litre of water; there were utilized four applications: 3 and 28 of may, 20 of june and 18 of july. 

Of the fungicides which were applied individualy the best one was the sistemic Difenoconazole (Score) with a dose of 1.5 cc, with 98.73% of sound apples, of the products which were applied in form of a mixture the best on was Myclo- butanil (Rally 40 W 0.75 g) + Dithane M-45 (Mancozeb 20 g) with an average of 97.98% of sound apples, the preventive action product Zineb (Flonex Z 400) a dose of 40 cc presented 91.93% of sound apples. The products, had a good con- trol, there were four applications in such a way that we have got a good fruit quality.