Powdery mildew control and yield response of inodorus melon

The research was carried out on melon (Cucumis melo L. var. inodorus Naud.) in 2006 and 2007 at “Pantanello” Experimental Farm (40° 24’N; 16° 48’E; 10 m a.s.l.; Metaponto, southern Italy) to evaluate the efficacy of a low environmental impact control strategy against powdery mildew of cucurbits. Winter melon was treated with a new anti-oidium formulation, called Stifénia, obtained from fenugreek seeds and stimulating the plant self-defence. The adopted experimental design included two control strategies (1. biological, using Stifénia and 2. conventional, using penconazole, myclobutanil and sulphur) and an untreated control (treated with water alone) applied to two cultivars of inodorus melon (cv ‘Amarillo’ and HF1 ‘Cocorito’, the latter a genotype resistant to powdery mildew). Stifénia applications were not effective against the disease; in fact, there were no differences in percentage of attacked plant surface between treated plots and untreated ones. The melon marketable yield was significantly higher with the conventional strategy respect to Stifénia and control. Repeated applications of Stifénia resulted in a significant decrease of marketable yield even in comparison with the untreated control. The cultivars significantly affected powdery mildew development, since the resistant one (‘Cocorito’) was attacked later and damaged always lower than the non-resistant genotype (‘Amarillo’). Laboratory analyses carried out on infected leaves always confirmed that Golovinomyces cichoracearum D.C. was responsible of the disease.