Nutrient Status of Cucumber Plants Affects Powdery Mildew (Podosphaera xanthii)

Abstract

We examined the effects of applications of N, P, K, Mg, and Ca through an irrigation solution and spraying K, Ca, and Mg salts on cucumber powdery mildew (CPM, Podosphaera xanthii) in potted plants and under commercial-like conditions. Spraying CaCl2 and MgCl2, or KCl and K2SO4, decreased CPM. There were significant negative correlations between the anion-related molar concentrations of the salts and disease severity. Among the sprayed treatments, NaCl provided significantly less CPM control when applied at a low (0.05 M) concentration, as compared with CaCl2 and MgCl2. When sprayed applications of Mg and K salts were analyzed separately from the untreated control, the Cl− salts were found to be more effective than the SO4−2 salts. High N and Mg concentrations in the irrigation water delivered to young, fruit-less cucumber plants reduced CPM, whereas more CPM was observed when the irrigation solution contained a medium amount of P and a high amount of K. In contrast, mature, fruit-bearing plants had less severe CPM at higher N, lower P, and higher K levels. Spraying mature plants with monopotassium phosphate, polyhalite (K2Ca2Mg(SO4)4·2H2O), and the salts mentioned above over an entire growing season suppressed CPM. CPM severity was also reduced by spray applications of Ca, Mg, and KSO4−2 and Cl− salts. Spray applications provided better CPM control than fertigation treatments. Induced resistance is probably involved in the effects of nutrients on CPM.

Unravelling Synergistic Effects of Palm Bunch Ash and Glutathione on Plant Growth

“…The white spots are indicative of powdery mildew, a fungal disease that favors hot and humid weathers [12]. The main cause of chlorosis is the lack of chlorophyll, which is often related to a deficiency in nutrients like magnesium and nitrogen as recorded from the soil test [20][21][22]. Chlorosis is often followed by wilting of the leaves, leading to a significant decrease in the mean number of leaves in the control group.…”

Effect of Mineral Nutrition and Salt Spray on Cucumber Downy Mildew (Pseudoperonospora cubensis)

“…Furthermore, high N and Mg concentrations in the irrigation water reduced the disease in young cucumber plants, and a medium amount of P and a high amount of K increased its severity. Mature cucumber plants had less severe powdery mildew at higher N, lower P, and higher K levels [7]. Spray application of P and K salts controlled cucumber powdery mildew [19].…”

“…The nutrient status of plant tissues essentially influences plant growth and productivity, pathogen infection, colonization, and sporulation [6]. Furthermore, the nutritional elements may increase or decrease the susceptibility of plants to certain diseases when used at various concentrations [5,7,8]. Plant nutrition may be administrated as part of the fertilization regime with irrigation water or as water-dissolved salts that are applied by spraying [1]; both approaches may affect plant diseases as demonstrated in recent studies with sweet basil diseases [8,9] and with cucumber powdery mildew [7].…”

“…Furthermore, the nutritional elements may increase or decrease the susceptibility of plants to certain diseases when used at various concentrations [5,7,8]. Plant nutrition may be administrated as part of the fertilization regime with irrigation water or as water-dissolved salts that are applied by spraying [1]; both approaches may affect plant diseases as demonstrated in recent studies with sweet basil diseases [8,9] and with cucumber powdery mildew [7]. The studies on sweet basil diseases caused by Sclerotinia sclerotiorum [10], Botrytis cinerea [11], Peronospora belbahrii [8,12], and tomato [13] revealed different effects of N, P, K, Ca, and Mg, depending on the plant host and the pathogen involved.…”

“H” sprayer effect on liquid deposition on cucumber leaves and powdery mildew prevention in the shed

“…1, have been developed ( Tang, 2002 ). However, powdery mildew species may vary with countries or regions within the same country ( Elad et al., 2021 ). In addition, the complexity and variability of the pathogen and the difficulty in identifying it accurately ( Cerkauskas and Ferguson, 2014 .…”