Efficacy of Milsana®, a Formulated Plant Extract from Reynoutria sachalinensis, against Powdery Mildew of Tomato (Leveillula taurica)

The efficacy of Milsana^® VP 1999 and 2000 (a formulated plant extract of Reynoutria sachalinensis), known to induce resistance to powdery mildew on cucumbers, was tested against Leveillula taurica (Lév.) Arn. on greenhouse tomato. In four out of five trials, Milsana^® achieved a disease reduction ranging from 42.2 to 64.6%. In one trial only, its efficacy was exceptionally low (23%). Application rates and disease pressure proved to be the main factors affecting the level of control. Milsana^® was significantly less effective than fungicides (alternated DMIs and penconazole) in situ. In contrast, Milsana^® was equally effective to wettable sulphur indicating that its effect was rather preventive than curative. The level of efficacy achieved by either Milsana^® or fungicides did not result in a significant increase of yield. Laboratory tests showed that Milsana^® (VP 1999) had a direct effect on conidial germination. Whether this effect significantly contributes to its field efficacy, remains to be elucidated. Overall, results indicate that Milsana^® could play an important role in disease management of powdery mildew in organic and low input tomato production.