The influence of crown rust (Puccinia coronata) on tiller production and survival of perennial ryegrass (Lolium perenne) plants in simulated swards

Abstract

Populations of Aberystwyth S23 and S24 ryegrass tillers were individually labelled and harvested at intervals to follow their life histories and productivity in response to the effect of infection with crown rust at two levels of nitrogen fertilization.The number of tillers in a population was reduced as a result of infection with crown rust. Increased rates of tiller death due to the pathogen occurred throughout the population age-range and were most pronounced in the youngest tillers. Population changes were evident following infection and continued to be apparent in the following spring. The disease caused alterations in sward age structure, leading both to a higher proportion of older tillers in the more rust-damaged treatments and to a decrease in the weight of the herbage produced. It is concluded that rust infection of a sward may lead to changes in population structure with long-term yield effects, in addition to the immediate direct yield reductions commonly reported. The significance of these results to the ecological and agronomic balance of grassland is discussed.

Effects of pathogens on perennial pasture grasses

“…In New Zealand, green matter losses of 53% in cv. Grasslands Ruanui have been recorded (Lancashire & Latch 1966, 1970, leading to clover dominance in mixed ryegrass/clover swards, and reductions in root weight, tiller number, and leaf area have been directly related to disease severity (Lancashire & Latch 1966;Plummer et al 1990). These results mirror similar findings from the United Kingdom, where infection has also been shown to alter the chemical composition of affected plants (Potter 1987).…”

Resistance to rust fungi in Lolium perenne depends on within-species variation and performance of the host species in grasslands of different plant diversity

“…A large number of studies have reported detrimental eVects of infestation with rust fungi on perennial ryegrass (review in Clarke and Eagling 1994). Infestation with crown rust may cause alterations in sward age structure of L. perenne, because the increase in tiller death is most pronounced in the youngest tillers (Plummer et al 1990). Potter (1987) reported on a reduced yield and tiller numbers of highly susceptible perennial ryegrass cultivars in comparison to resistant cultivars that persist for three regrowth cuts after infestation with crown rust.…”

Four QTLs determine crown rust (Puccinia coronata f. sp. lolii) resistance in a perennial ryegrass (Lolium perenne) population

“…In species grown for their vegetative organs, such as L. perenne, foliar diseases are especially important as they are often correlated with reductions in yield and quality. This is the case for crown rust infections caused by the biotrophic fungus Puccinia coronata (Potter, 1987;Plummer et al, 1990). The severity of crown rust infections can be reduced by good management practices, such as the use of resistant cultivars (Van Bockstaele and Baert, 2004).…”