Pest status of the sooty blotch and flyspeck complex in Asturian (NW Spain) apple orchards

摘要

Sooty blotch and flyspeck (SBFS) fungi occur on apple surface in regions with moist climate, such as Asturias, in the Northwest coast of Spain. Due to the lack of knowledge on SBFS in our region, research has been conducted to determine (1) the timingof appearance of symptoms, (2) the incidence of these fungi on different cultivars, orchards and years and (3) the effectiveness of several fungicides for controlling this disease. Development of SBFS signs was followed in the 2011 season from early July to harvest in several cultivars and orchards. SBFS signs were observed from July 20 onwards. Signs classically related to SB and those of FS appeared on the same date. Some variation in symptom development was observed among cultivars and orchards. Cultivar susceptibility was recorded just before harvest in 2010 and 2011. The severity of SBFS depended greatly on the cultivar but also on the orchard. Damage level in individual cultivars and orchards was rather similar in the two years of observation. Lime sulphur and potassium bicarbonate (Armicarb) sprayed alone or combined with wettable sulphur provided good control of SBFS when they were applied fortnightly from early June to late September (9 sprayings). The clay Myco-San was not as efficient at controlling fruit blemish although diminished the symptoms compared to untreated trees. The use of potassium bicarbonate had, however, side effects increasing lenticel spotting to intolerable limits and reducing fruit weight and yield. This study allowedus to determine the importance of the disease and the cultivar susceptibility in our conditions. Further research is needed to develop a forecasting model and to use fungicides more efficiently.