摘要:

In northern Queensland, the addition of 2,4,5‐T butyl ester was found to be unnecessary to maintain the control ofEchinochloa colona(L.) Link andCyperus IriaL. In dry seeded rice when propanil rates were reduced below the registered rate of 4 kg a.i. ha−1. Adequate weed control was obtained with 1.3 kg a.i. ha−1propanil alone. No adverse effects on rice yield were found with any of the propanil × 2,4,5‐T treatments. Low rates of propanil, 1.3 and 0.72 kg a.i. ha−1, compared favourably with pre‐emergence treatments of thiobencarb, butachlor, oxyfluorfen and pretilachlor (plus a safener) when weed yields were low. Where water management was poor andIschaemum rugosumSalisb. was the dominant weed, oxyfluorfen applied pre‐emergence at 0.96 kg a.i. ha−1produced a higher rice and a lower weed yield than the low rates of propanil. In three of the five experiments, weed growth was insufficient to depress rice yields significantly.

ISSN:0143-6147    

DOI:10.1080/09670879209371715

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Zea maysin Latin America is affected by a disease complex known as tarspot caused byPhyllachora maydis, Monographella maydisandConiothyrium maydis.Two series of pictorial standard diagrams were developed for field assessment, one forP. maydisand the other forP. maydis + M. maydis.The disease severity depicted on the 72 diagrams was assessed for the number of lesions and the percentage disease severity by 36 volunteers of diverse professional backgrounds without prior experience in assessing crop diseases. The assessment error for theP. maydisdiagrams included a 17–38% underestimation of number of lesions and a 184–330% overestimation of disease severity. For theP. maydis × M. maydisdiagram, overestimation for the classes with 1.0–4.5% disease severity was relatively high, whereas the error diminished with a higher proportion of larger lesions. In general, regular distribution of disease tends to be overestimated, in this case by 10–71%. The greatest assessment error was, however, related to the inappropriate choice of assessment scale, particularly for lesions smaller than 3.5 mm.

ISSN:0143-6147    

DOI:10.1080/09670879209371716

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

No difference in plant mortality occurred when either Blue Star (highly susceptible) or PI 201234 (highly resistant) was inoculated with four isolates ofPhytophthora capsici.One isolate caused more plant mortality on Szechwan (moderately susceptible) than the other isolates. No symptoms were observed on PI 201234 when inoculated with 105zoospores/ml; Szechwan wilted at 105zoospores/ml. Blue Star plants died at 105zoospores/ml and wilted at 102zoospores/ml. When inoculated at different plant ages, PI 201234 did not wilt, however Blue Star wilted and died at all ages tested. Younger and older plants of Szechwan had less disease than plants of intermediate age. Two new sources of highly resistant genotypes are reported.

ISSN:0143-6147    

DOI:10.1080/09670879209371717

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Methyl bromide and dazomet fumigants were applied to soil at the rate of 454 kg/ha a.i. to determine their effects on viability ofTilletia indicateliospores. At 5 and 10 cm depth, the teliospore germination was 0 and 0.02%, and 2.41 and 0.60%, in plots treated with methyl bromide and dazomet, respectively. In the untreated control plot, germination was 9.91 and 7.16%.

ISSN:0143-6147    

DOI:10.1080/09670879209371718

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The lesion nematode,Pratylenchus goodeyihas been found to be a major problem of ensete (Enseteventricosum)in Ethiopia, and is also recorded on banana and in association with the bacterial wilt disease caused byXanthomonas campestrispv.musacearum.The implications of this bacterial/nematode complex are potentially serious for both crops, but especially for ensete, which is a starch staple for about 7 million people in Southern Ethiopia.

ISSN:0143-6147    

DOI:10.1080/09670879209371719

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A farm survey of 915 rice farmers in the Muda area showed that about 80% of the farmers own sprayers. The lever operated knapsack (LOK) sprayer is most popular. They are sold in over 30 brand names, mainly in retail and hardware shops. Sprayers owned are generally between 3–6 years old. About 76% of the farmers said that they are considering buying a sprayer in the near future. The most popular choice is the LOK sprayer with a tank capacity of about 3 gallons and a price range of between M$50–100 (US$19–38). Farmers are not aware of the newer spray methods, such as controlled droplet application, tractor‐mounted sprayers and fogging machines. About 93% had never attended any training course on crop spraying or sprayer maintenance. In case of problems with sprayers, they normally do not seek help. Most farmers said they normally clean the sprayers using water f rom the irrigation canals after each use. Nozzles are also cleaned but are seldom replaced. It is apparent from the survey that there is an urgent need for more training programmes on spraying techniques and sprayer maintenance for rice farmers in the Muda area. The LOK sprayer is likely to remain as the main spray equipment and efforts should be made to improve them, both in research and in improving use efficiency. There is great variation in quality of the various brands available. Minimum standards should be set to prevent the sale of poor quality sprayers, which will contaminate the operators. Agricultural authorities should consider establishing centres or ‘sprayer clinics’, where farmers can obtain advice, repairs and training on spray equipment.

ISSN:0143-6147    

DOI:10.1080/09670879209371720

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670879209371721

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670879209371722

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670879209371694

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor