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Lower level of nitrogen ensures better resistance to mildew

April 27, 2023  By Greenhouse Canada

April 26, 2023 -A study by Greenhouse Horticulture and Flower Bulbs Business Unit of the Netherland’s Wageningen University & Research (WUR) looked into the impacts nitrogen had on mildew in the cultivation of gerbera, sweet pepper, and cucumber.

WUR investigated the effect of a lower level of nitrogen on the growth and resilience of cucumber, bell pepper, chrysanthemum, and gerbera.

The study found that “nitrogen levels can be reduced in all crops.”


For cucumber, a nitrogen reduction of over 30 per cent resulted in a negative effect on growth and production. The limiting value was lower for chrysanthemum, gerbera, and bell pepper, where the effect on growth and production occurred only from a 70 to 80 per cent reduction in nitrogen compared to normal.

“The nitrogen uptake by the plant also has an effect on the susceptibility to powdery mildew, especially in gerbera and cucumber. However, a lower level also causes less growth,” the report states.

The study also examined whether the use of elicitors, like as jasmonic acid or salicylic acid, have additional effects. Observations found that the effects were equal to lowering the nitrogen level.

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