Biochemical and environmental factors responsible for development of powdery mildew disease of pea and its management through nutrition and systemic acquired resistance

Pea (Pisum sativum L.) is a grain legume which is cultivated worldwide due to its high nutritious value. Powdery mildew is a common disease of field pea, and is caused by the ascomycete, fungus Erysiphe pisi. A field studies were conducted at plant pathology' department, University of Agriculture Faisalabad to evaluate thirteen Pea cultivars for screening against Powdery mildew during winter 2013. The disease incidence data was recorded and analyzed by using. LSD design at 0.05% probability level. The disease severely infected the varieties "Climax and Mateor" up to the maximum at 74% and 73.5%. Three cultivars F-16, No.267 and Peas 2009 were found resistant at 3.3%, 6.6% and 1.6 % of mean disease incidence respectively. The significant positive correlation was observed with four of the environmental variables maximum, minimum air temperature, relative humidity between wind velocity of powdery mildew disease on all of pea varieties used. Maximum disease incidence was recorded in Green grass (60%), at maximum temperature of 28 degree C and minimum 15 degree C. The highest D.I more than 60% was recorded in Green grass at 88% relative humidity. Wind velocity was positively correlated with D.I maximum disease was developed at 4.5 km/h. -ive effect of rain fall was observed on all varieties and the effect of disease on the P, Ca, Mg, Zn, Cu and Fe contents of pea leaves which were measured by collecting 6 varieties of pea from which 3 resistant (Peas 2009, No.267 and F-16), 1 moderately susceptible (PF-450) and 2 susceptible (Climax and Mateor) for biochemical analysis. Results showed that among six contents (P, K, Ca, Mg, Zn and Fe) potassium, calcium and zinc contents were higher in diseased ones while phosphorus, Iron, magnesium contents were decreased in diseased leaves as compared to healthy leaves in both reaction groups (resistant, susceptible). The 5 plant activators (Salicylic acid, Benzoic acid, KH2PO4, K2HPO4 and Citric acid) gave significant control and salicylic acid at concentration 1.5 was most significant in managing powdery mildew disease of pea during in vivo experiment. The macro and micro nutrients were applied at 0.5%, 0.75%, and 1% in-vitro experiment to control powdery mildew of pea. All treatments of macro and micro nutrients applied gave significant results against powdery mildew disease of pea. Macronutrient (N, P and K) application at concentration 1 % gave most significant results. Lab experiments were laid out according to completely randomized design (CRD) while field experiments were laid out according to Randomized completely block design (RCBD) and Nested design were used for biochemical analysis.