Perennial ryegrass is the most abundant grass species in temperate climates. An increased herbage intake of dairy cows by breeding new cultivars could have a large potential impact on agriculture. The effects of cultivars on sward structure, nutritive value, physical characteristics and disease resistance of perennial ryegrass are discussed. Cultivar differences were found in several studies fo...

Fungus-growing ants, their cultivated fungi and the cultivar-attacking parasite Escovopsis coevolve as a complex community. Higher-level phylogenetic congruence of the symbionts suggests specialized long-term associations of host-parasite clades but reveals little about parasite specificity at finer scales of species-species and genotype-genotype interactions. By coupling sequence and amplified...

Polyploidy, ploidal variation between populations, and aneuploidy within some populations complicate population genetic analyses in switchgrass. We report 21 genic-simple sequence repeat marker loci with single-locus disomic segregation in tetraploids and apparently tetrasomic inheritance in octoploids, thus allowing population genetic analyses across ploidy levels. Based on 472 individuals sam...

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a highly destructive pest of onion, Allium cepa L., and its management relies on multiple applications of foliar insecticides. Development of insecticide resistance is common in T. tabaci populations, and new strategies are needed to relax existing levels of insecticide use, but still provide protection against T. tabaci without...

In this study, the effect of 20 barley cultivars were evaluated on the life table parameters and digestive enzymatic activity of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) under laboratory conditions (28 ± 1°C, 60 ± 5% RH, and a photoperiod of 16:8 (L:D) h). Among barley cultivars tested developmental time of R. dominica immature stages was longest on cultivar ...

The objective of this work was to morphologically characterize 15 banana cultivars and assess the physical and chemical characteristics of their fruits at two maturation stages, unripe (pre-climacteric) and ripening. The plants were evaluated regarding their pseudostem height and diameter, petiole length, leaf blade length, width and length-to-width ratio. The cultivar Ouro had fruits with lowe...

ABSTRACT A precise real-time polymerase chain reaction (PCR) assay was developed for quantifying Verticillium albo-atrum DNA. The assay was used in a repeated experiment to examine the relationship between the quantity of pathogen DNA detected in infected leaves and shoots and the severity of Verticillium wilt symptoms in several alfalfa cultivars expressing a range of disease symptoms. Plants ...

Environ. Entomol. 22(2): 432-437 (1993) ABSTRACT Bacillus thuringiensis Berliner toxicity is a dose-dependent phenomenon, and the dose acquired by an individual is directly related to the quantity of treated food consumed. A bioassay was conducted using two Apium graveolens var. rapaceum (L.) cultivars to determine if the B. thuringiensis dose acquired by Spodoptera exigua (Hiibner) (Lepidopter...

Printed on recycled paper SUMMER 2001 24 A Healthy Ecosystem Inconsistent performance of biological control strategies for turfgrass disease control has limited the adoption of this technology into IPM programs. A major contributing factor to this variable performance in agricultural systems is the cultivar to which biological control organisms are applied. In a recent study, our goal was to de...

Comparisons of phylogenetic patterns between coevolving symbionts can reveal rich details about the evolutionary history of symbioses. The ancient symbiosis between fungus-growing ants, their fungal cultivars, antibiotic-producing bacteria and cultivar-infecting parasites is dominated by a pattern of parallel coevolution, where the symbionts of each functional group are members of monophyletic ...