Effect of foliar‐applied potassium chloride on septoria leaf blotch of winter wheat

Abstract

The effect of foliar-applied potassium chloride on Septoria tritici , the anamorph of Mycosphaerella graminicola , was quantified and possible modes of action investigated during controlled-environment and field experiments. A field experiment in harvest year 1997 showed c . 50% reduction in the area of leaf 2 of winter wheat plants affected by septoria leaf blotch after foliar application of potassium chloride, compared with untreated controls. Similarly, in harvest year 1998 potassium chloride reduced, by about one-third, the area of the flag and penultimate leaf affected by S. tritici . However, a significant yield increase was not observed, although grains m − 2 did show an increase of borderline significance.Applications of epoxiconazole reduced the area of leaf 4 affected by S. tritici compared with untreated controls, whereas applications of chlorothalonil, potassium chloride or polyethylene glycol proved ineffective against disease development. This may suggest that potassium chloride is relatively immobile and possesses contact activity similar to that of chlorothalonil. In 1998, similar reductions in leaf area affected were observed with the inert osmoticum polyethylene glycol in the field, suggesting that the control provided by potassium chloride may be achieved by adverse osmotic effects on the pathogen. Scanning electron microscopy of germinating conidia on wheat plants showed inhibition of conidial germination by both potassium chloride and polyethylene glycol at the same calculated osmotic potential on the leaf surface.

Improving phosphorus uptake and wheat productivity by phosphoric acid application in alkaline calcareous soils

“…Wheat ( Triticum aestivum L.) is the major cereal crop widely grown throughout the world and is largely produced in Pakistan for daily consumption by people as staple food . Although annual production of wheat in this country is more than 20 million tons, the average national yield is far lower than the potential yield . Among various other factors, low nutrient availability to the growing crop is considered a major factor responsible for this decline in yield.…”

Chemical inducers for resistance induction against powdery mildew of cucumber under greenhouse conditions

“…The probable mode of action of the tested inducers against powdery mildew of cucumber may be due to its ionic components and its adverse effect on enzyme activities of the pathogen (Biggs et al, 1997;Miceli et al, 1999) or a contact osmotic mechanism * Means in a column followed by the same letters are not significantly different using Duncan's multiple ranges test at the phylloplane level (Mann et al, 2004). The mechanism of phosphate salts action against powdery mildew fungus in cucumbers not clearly identified till now.…”

Managing Crop Disease through Cultural Practices

“…Foliar-applied potassium chloride has been shown to control Blumeria graminis and Septoria tritici on wheat in fi eld studies (Cook et al, 1993;Mann et al, 2004), probably due to osmotic effects on the fungal pathogens, disrupting pathogen development and subsequent infection (Kettlewell et al, 2000;Mann et al, 2004).…”