During July 2004, head rot of cabbage ( Brassica oleracea var. capitata ) and web blight of snap bean ( Phaseolus vulgaris ) were frequently observed in Dehong district in southern Yunnan Province, China. Affected cabbages had a dark, sometimes wet decay at the bases of outer leaves and on emerging cabbage heads. The outer leaves later collapse. A brown mycelium appeared on affected parts after damp weather with occasional small brown sclerotia on the cabbage head. The first symptoms on snap bean were small, circular, watersoaked spots on stems, pods, and foliage, later tan-brown with a dark border, up to 2 cm across. Irregular, light brown sclerotia and a fine mycelium develop as plants become seriously blighted. Affected plant parts from cabbage and snap bean were surface-sterilized and incubated on potato dextrose agar (PDA). Rhizoctonia solani was recovered consistently. All cabbage and snap bean isolates anastomosed with tester isolates of subgroups HGI, HGII, and HGIII within AG-4, giving a C2 hyphal fusion reaction (Carling, 1996). The 5·8 s rDNA-ITS of four cabbage and snap bean isolates (CA-04 -1, CA-04 -2, SB-04 -1 and SB-04-2 respectively) matched isolates of R. solani AG-4, subgroup HGI (Kuninaga et al ., 1997).Cabbage heads and snap bean green pods were inoculated with two of their respective isolates grown for 4 days on PDA. After covering with moist cotton to avoid drying out, test plants were held in a greenhouse with ∼ 28 ° C-16 h day and 15 ° C-8 h night. Plugs of sterile PDA were placed on cabbage and snap bean plants as controls. These remained healthy while, within one week, inoculated cabbage and snap bean plants showed similar symptoms to those seen naturally. Rhizoctonia solani was reisolated from these plants, confirming its pathogenicity. This is first report of Rhizoctonia solani AG-4 HGI in China causing head rot of cabbage and web blight of snap bean. AG-A infects snap bean in China (Yang et al ., 2005) and AG-4 in Iran (Balali & Kowsari, 2004), but through root infections. Rhizoctonia solani routinely affects cabbages and further study is needed to compare the pathogenicity of isolates in relation to their sub-groups.

Purpose Which kind of elements could be determined by the portable X-ray Fluorescence (PXRF) analyzer in field conditions? How about the accuracy of the results? It is necessary to conduct some researches in order to well understand the application of PXRF which is regarded as a new kind of in-situ measurement method. Methods A set of 221 farmland soil samples were collected within a basin once it has been a lead-zinc smelting base. PXRF was used for field detection at all sample sites, then the soil samples were brought back to the laboratory to be analyzed again by atomic absorption spectrometry (AAS), paired T test and linear regression were conducted to analyze the difference and correlation between the result of PXRF and AAS methods. Results There was little difference and high correlation between PXRF and AAS methods, indicating that in field conditions PXRF can effectively predict the concentrations of Pb and Zn in soil. Although there were some differences in the determinationresults of Cu, the pollution level of Cu in this study area still could be predicted. Unfortunately, PXRF method had large errors in the determination of Cd and Cr, so it was not suitable for the in-situ determination of Cd and Cr in this study area. Conclusion The concentrations of Pb and Zn in the soil of lead-zinc smelting area can be accurately monitored by PXRF, while concentrations of Cu in soil can also be predicted by PXRF in the less accuracy level, Cd and Cr should not be monitored by PXRF.