The alternative control of powdery mildew complex (Leveillula taurica and Erysiphe sp.) in tomato in the Azapa Valley, Chile

Abstract

G. Sepúlveda-Chavera, R. Salvatierra-Martínez, and R. Andía-Guardia. 2013. The alternative control of powdery mildew complex (Leveillula taurica and Erysiphe sp.) in tomato in the Azapa Valley, Chile. Cien. Inv. Agr. 40(1):119-130. The powdery mildew complex (Leveillula taurica and Erysiphe sp.) is one of the major factors limiting tomato (Solanum lycopersicum) production in the Azapa Valley, Chile. This problem is especially severe in the case of protected crops because the options for the treatment of these crops with chemical fungicides are limited. This study evaluated the effects of 0.5 and 1.0 kg·100 L -1 Ospo-V55® and 10% raw cow's milk on tomato leaflets infected by powdery mildew complex. Ospo-V55®, with active ingredients consisting of 10% p/p of algae extract (IB-101) and 0.8% of microorganism concentrate, was evaluated in this study. Ospo-V55® contains flavonoids, alkaloids and phenols, oligo-and polysaccharides, 8.6% protein, 0.5% magnesium and trace amounts of riboflavin, niacin and ascorbic acid. Tacora Mas® (a mixture of 25% tebuconazole and 12.5% carbendazime) and Acoidal WG (wettable sulfur) were included for comparison with the Ospo-V55® and raw cow's milk treatments. A diagrammatic scale to assess the severity of the disease was validated and used to quantify the damage resulting from tomato powdery mildew and the effects of the treatments. The effect of the treatments on the germination of the conidia of L. taurica and Erysiphe sp. was also studied on water agar. Tacora Mas® provided the best control of powdery mildew in the field, followed by 1.0 kg·100 L -1 Ospo-V55® and Acoidal. However, Ospo-V55® was more effective than Acoidal. All treatments, including raw cow´s milk, significantly (P≤0.05) reduced disease severity in the leaf compared with the control. Both surfaces of the leaves were assessed, and better results were obtained on the upper surface. This difference was associated with differences in wetting. Acoidal was the most effective treatment for inhibiting conidia germination, decreasing germination more than 98.2%. This result differed significantly from the value of inhibition produced by Tacora Mas®. Ospo-V55® and raw cow´s milk showed significant differences (P≤0.05) in conidial germination compared with the control. Based on these results, we conclude that Ospo-V55 and raw cow´s milk can be used in an integrated management program as alternative treatments to control tomato powdery mildew complex.

Bokashi, Boiled Manure and Penergetic Applications Increased Agronomic Production Variables and May Enhance Powdery Mildew Severity of Organic Tomato Plants

“…Powdery mildew severity was assessed using a diagrammatic scale proposed by Sepúlveda-Chavera et al [21]. Six plants were randomly chosen, and on each plant three leaflets were chosen on lower, mid, and upper thirds of the plant, totaling nine observations per plant.…”

Characterization of powdery mildew (Leveillula taurica) in globe artichoke (Cynara scolymus)

“…The causal agent (Leveillula taurica) of powdery mildew of globe artichoke is an obligate fungus infecting a wide range of economically important crops such as pepper, tomato, eggplant, onion and cotton (Zheng et al 2013a). For example, in South and North America, yield losses from L. taurica are frequently reported in tomato and potato production areas (Glawe et al 2004;Sepúlveda-Chavera et al 2013). Yield losses caused by L. taurica reachs up to 40% in pepper production in Puerto Rico (Negron et al 1991).…”