Uromyces appendiculatus (bean rust)

Kale and Anahosur (1996) reported that triadimefon and mancozeb sprays were effective in controlling U. appendiculatus on cowpeas grown at Dharwad, India; diclobutrazol reduced disease spread after one spray application. Gonzalez and Garcia (1996) found that the best results against U. appendiculatus on Phaseolus vulgaris were obtained with bitertanol, hexaconazole and oxycarboxin sprays. No significant differences were found among the treatments, which statistically excelled sulfur and raised yield significantly compared with sulfur. Becerra Leor et al. (1994) reported that in Mexico fungicide treatment applied to susceptible varieties such as Jamapa increased seed yield by >200 kg/ha. Fungicides that gave the best results were hexaconazole, maneb and tebuconazole applied before flowering.

Grafton et al. (1997) reported that bean cultivar Maverick is homozygous dominant for the resistance gene Ur3, which confers resistance to prevalent races of U. appendiculatus in North Dakota, USA.Rosas et al. (1997) reported that cultivar Tio Canela-75 was resistant to U. appendiculatus and is recommended for low and intermediate altitude <1200 m) bean production regions of Central America.Pedroza et al. (1994) reported that in experiments to determine the effect of five Phaseolus vulgaris cultivars, crop densities, two nitrogen levels and two nitrogen sources on root rot and foliage diseases it was concluded that Amarillo Zaragoza or Bayo Zaragoza at a medium density of 71,000 plants/ha and with low rates of inorganic nitrogen would be the best option when root rot, bacterial blight and rust are the most important diseases.Panse et al. (1997) reported that in tests using a mixture of rust resistant and susceptible plants of common bean (Phaseolus vulgaris) rust inoculated mixtures containing resistant, intermediate and susceptible genotypes, yield increased by 3.3% compared with the control. In mixtures of P. vulgaris a higher proportion of resistant lines was required, compared with cereals, for comparable reductions in the spread of disease, due to lower plant density and correspondingly higher autodeposition rate of urediospores.Cherian et al. (1996) investigated 18 genotypes of cowpea (Vigna unguiculata) which were evaluated for slow rusting (a resistance mechanism) using the genotype C152 (highly susceptible to rust) as a control. Observations for leaf area covered and pustule density were recorded at 2-8 day intervals, starting from the first appearance of rust. Based on logistic and Gompertz growth rates and AUDPC values, several genotypes including V38, APC813, APC83 and V17 were identified as possessing favourable slow rusting behaviour. Fininsa (1996) reported the results of a study on the effect of intercropping P. vulgaris with maize on rust caused by U. appendiculatus under three cropping systems: mixed intercropping, row intercropping and sole cropping of P. vulgaris using five cultivars in a randomized complete block design. Mixed intercropping reduced rust incidence levels on average by 51 and 25% compared with sole cropping and row intercropping, respectively.Kale and Anahosur (1993) found that in a field experiment early sowing dates resulted in a lower disease index and higher yield. Weather conditions were more conducive to disease spread later in the growing season and caused heavy infection at earlier stages of the crop when sowing was delayed. Kelly et al. (1995) reported that P. vulgaris cv. Newport (PI586656) carries the Ur3 gene which conditions resistance to U. appendiculatus race 53 and all indigenous races prevalent in Michigan, USA.

Centurion and Kimati (1994) reported that Bacillus subtilis, Bacillus sp. and Arthrobacter sp. controlled U. appendiculatus on Phaseolus vulgaris by >95% when used as concentrated cell suspensions in aqueous Tween 20 solutions. Low concentration suspensions decreased rust pustule number by >80% using B. subtilis and Bacillus sp. and by 70% using Arthrobacter sp. The B. subtilis and Bacillus sp. isolates as concentrated suspensions partially reduced spore viability of U. appendiculatus. B. subtilis and Arthrobacter sp. reduced rust pustules more in the greenhouse than Bacillus sp. Centurion et al. (1994) studied the antagonists Bacillus sp. isolate B206, B. subtilis AP401 and Arthrobacter sp. B138. In liquid culture the Bacillus isolates reduced the number of bean rust pustules by >95%. Arthrobacter sp. was less efficient, giving a reduction of 65%. The B. subtilis isolate released thermostable substances antagonistic to U. appendiculatus into the culture media; the liquid culture as well as the filtrate and autoclaved culture reduced pustule number by >95%. Isolate B206 was also found to act through thermostable substances released into the medium, but the greatest efficiency was noted when living cells of the antagonist were applied to the plant. Production of antagonistic substances by isolate B206 was affected by NaCl concentration in the medium. Arthrobacter did not act through antibiosis. Mizubuti et al. (1995) found isolates of B. subtilis which, by means of broth culture supernatants, were able to reduce the number of rust pustules; isolates FF-1, FF-5 and FF-6 were selected as potential biocontrol agents.Romero and Carrion (1995) evaluated the pathogenicity of V. lecanii on U. appendiculatus var. appendiculatus, the cause of Phaseolus vulgaris rust disease, and the best time for its application as a biological control agent of rust under greenhouse conditions. The rust infection on P. vulgaris was reduced by between 39 and 52% compared with controls. Pohrenezny et al. (1987) recommended the use of mancozeb + sulfur followed by chlorothalonil for control of rust on beans in Florida, USA.