Phenotyping Brachiaria Genotypes to Assess Rhizoctonia Resistance by Comparing Three Inoculum Types.

Rhizoctonia foliar blight, caused by Rhizoctonia solani, is an important disease of Brachiaria spp. in tropical America. Host-plant resistance is an attractive option for disease management.

Characterization of resistance to adult spittlebugs (Hemiptera: Cercopidae) in Brachiaria spp.

Nymphs and adults of several spittlebug (Hemiptera: Cercopidae) species are key pests of forage brachiariagrasses (Brachiaria spp.) in tropical America. To support current breeding programs, a series of experiments aimed at characterizing the mechanisms of resistance to adult feeding damage were carried out.

Diversity of Rhizoctonia spp. Causing Foliar Blight on Brachiaria in Colombia and Evaluation of Brachiaria Genotypes for Foliar Blight Resistance.

Up to 50% of Brachiaria production in the tropics is affected by foliar blight caused by Rhizoctonia spp. Monothallic isolates of Rhizoctonia (n = 147) were cultured from different Brachiaria genotypes in Colombia and morphologically characterized and evaluated in pathogenicity trials in the greenhouse. Based on restriction fragment length polymorphism of the internal transcribed spacer region, 101 of the isolates were identified as Rhizoctonia solani anastomosis group (AG)-1 IA and were multinucleated, with high growth rate, brown mycelium, and high virulence; and 46 isolates were identified as Rhizoctonia sp.

Characterizing herbivore resistance mechanisms: spittlebugs on Brachiaria spp. as an example.

Plants can resist herbivore damage through three broad mechanisms: antixenosis, antibiosis and tolerance(1). Antixenosis is the degree to which the plant is avoided when the herbivore is able to select other plants(2). Antibiosis is the degree to which the plant affects the fitness of the herbivore feeding on it(1).

Independence of resistance in Brachiaria spp. to nymphs or to adult spittlebugs (Hemiptera: Cercopidae): implications for breeding for resistance.

Both nymphal and adult spittlebugs (Hemiptera: Cercopidae) cause serious economic damage to susceptible brachiariagrass [genus Brachiaria (Trin.) Griseb], pastures in tropical America. Both life stages are xylem feeders: nymphs feed primarily on roots and stems, whereas the adults feed mainly on foliage.

Screening for resistance to adult spittlebugs (Hemiptera: Cercopidae) in Brachiaria spp.: methods and categories of resistance.

Both nymphal and adult stages of several species of spittlebugs (Hemiptera: Cercopidae) are key economic pests of brachiariagrasses (Brachiaria spp.) in tropical America. Progress has been made in the characterization and development of antibiosis resistance to nymphs in brachiariagrasses.

Sublethal effects of antibiosis resistance on the reproductive biology of two spittlebug (Hemiptera: Cercopidae) species affecting Brachiaria spp.

Several greenhouse experiments were used to measure how high levels of antibiosis resistance to nymphs in two interspecific Brachiaria (brachiariagrass) hybrids affect life history parameters of the spittlebugs Aeneolamia varia (F.) and Zulia carbonaria (Lallemand), two of the most important spittlebug (Hemiptera: Cercopidae) species affecting Brachiaria production in Colombia. The A.

Response of resistant and susceptible Brachiaria spp. genotypes to simultaneous infestation with multiple species of spittlebugs (Hemiptera: Cercopidae).

The response of one susceptible and three resistant Brachiaria spp. (Hemiptera: Cercopidae) genotypes to individual or combined attacks by nymphs of Aeneolamia varia (F.), Aeneolamia reducta (Lallemand), Zulia carbonaria (Lallemand), and Zulia pubescens (F.

Antibiosis and tolerance to five species of spittlebug (Homoptera: Cercopidae) in Brachiaria spp.: implications for breeding for resistance.

Several genera and species of spittlebugs (Homoptera: Cercopidae) are economic pests of Brachiaria spp. grasses in tropical America. To support current breeding programs aimed at obtaining multiple spittlebug resistance, we undertook a series of studies on antibiosis and tolerance as possible mechanisms of resistance to five major spittlebug species affecting Brachiaria spp.