摘要:

Experiments in the North and Atlantic Coastal areas of Honduras determined the critical period of competition ofRottboellia exaltata(itchgrass) with maize, and established cultural and chemical methods for control. The critical period of competition lies between 30 and 45 d after planting; plots should be kept weed free during this period to avoid significant reduction in yield. UnweededR. exaltatareduced maize yield by about 80%. Among control treatments, a combination of atrazine and pen‐dimethalin at 1–2 and 1–3 kg a.i./ha gave the highest yield. Supplementary post‐emergence control by hoeing or using paraquat could help attain yields comparable to those obtained in the plots kept weed free throughout the growing period.

ISSN:0143-6147    

DOI:10.1080/09670878609371039

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Herbicides (fluchloralin, methabenzthiazuron, diuron oxyfluorfen, simazine, thiobencarb and alachlor), organic mulch and intercropping with cowpea (Vigna unguiculataL. Walp) and blackgram(Vigna mungo L.), In comparison with unweeded and weed free check, were studied during the rainy seasons (July‐Sept) of 1982 and 1983 in a 2 year crop of medicinai yam. Simazine 2 kg/ha was most effective in arresting weed dry matter but like other herbicides was phytotoxic to medicinal yam. The weed free check gave maximum tuber yield. Organic mulch, yam plus cowpea and yam plus blackgram were similar in effect and superior to any of the herbicides. The yam plus blackgram association proved most economical due to the additional grain yield of 10–5 and 8 q/ha obtained in the first and second years of study, respectively.

ISSN:0143-6147    

DOI:10.1080/09670878609371040

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Rice yield increased significantly and consistently up to 120 kg N/ha when weeds were not controlled. But when weeds were effectively controlled by two hand weedings (20 and 40 days after transplanting) or by use of thiobencarb at 1–0 kg a.i./ha rice yield increased significantly up to 80 kg N/ha. The optimum dose of N for transplanted rice under mid‐hill conditions of Himachal Pradesh (Palampur) was 82 kg/ha when two hand weedings were done and 86 kg/ha when weeds were managed using thiobencarb. The yield response per kg of N in the respective treatments was 20 and 24 kg of grain. The weed dry weight was significantly lower in thiobencarb and hand weeded plots compared with unweeded check though the difference in weed dry weight due to the former two treatments was not significant.

ISSN:0143-6147    

DOI:10.1080/09670878609371041

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Tencurrentlyrecommended tomato cultivars were grown during three wet seasons at three locations in Northern Nigeria to assess the benefit of a fungicide spray programme in the control of leaf diseases. Average yield reductions of 25.2, 41.3 and 51.7% were obtained at Kadawa, Samaru and Yandev respectively when the crops were left unprotected. Although cultivar response was not always consistent, the processing‐type tomatoes such as Roma VF, Harvester and Marzanino appeared to have some field resistance to leaf diseases compared to the fresh market tomatoes Ife 1 and La Bonita.

ISSN:0143-6147    

DOI:10.1080/09670878609371042

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The infectivity of sap plus trash from the roots of naturally diseased cotton plants with typical symptoms ofFusariuminfection from endemic wilt areas, particularly in the Managil scheme, was found to be quite intense. Not only was the percentage of diseased plants high when adopting such a ‘Trash Inoculum’ technique, but also very drastic symptoms developed on the test plants. This was the case when testing several cotton cultivars, amongst which were those commercially grown throughout the Gezira and Managil schemes, e.g.Gossypium barbadenseL. cv. Barakat and 6.hirsutumL. cv. Barac (67)B. The usefulness of the technique in a breeding programme or extension communication is briefly discussed.

ISSN:0143-6147    

DOI:10.1080/09670878609371043

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Bacterial red stripe (BRS) was observed on sugarcane (Saccharum officinarumL.) at the National Agricultural Research Centre (NARC), Islamabad during spring of 1984–85. Isolations from diseased plants yielded yellow, circular, convex colonies. The bacteria were gram negative, rod shape measuring 0.6–0.7 x 1.5–1.6/μm, catalase positive, oxidase negative and induced necrotic spots on tobacco leaves(Nicotiana tobacum).This organism was identified asPseudomonas rubrilineanson the basis of biochemical, physiological and pathgenicity tests. This is believed to be the first identification of this bacterium from Pakistan. Out of 9 sugarcane cultivars tested, 5 remained moderately resistant, 2 susceptible and 2 moderately susceptible.

ISSN:0143-6147    

DOI:10.1080/09670878609371044

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Details of the field trials which led to the discovery of an insecticide efficacious against both bug (Nezaraspp.) and borer(Cryptophlebiaspp.) attacking the fruit of macadamia in Malawi are given. Cypermethrin as a 002% a.i. mist application has been shown to be the best all‐round insecticide but in the absence of borer a 0.1% a.i. application of fenitrothion was more effective in bug control. Fenthion was also found to reduce bug damage considerably. Details are given of initial field work with the synthetic female sex pheromone ofCryptophlebia batrachopaMeyr. and C. leucotretaMeyr. A microcapsule preparation which could be poured into the mist‐blower and mixed with insecticide was found to be as effective in reducing damage as a vial and sticky trap method. Early work with ultra low volume (ULV) preparations of endosulphan, fenitrothion and cypermethrin are also reported. Some reduction in borer damage was obtained whenBacillus thuringiensisBerliner preparations were applied weekly in combination with 0.1% a.i. fenitrothion but the effect was lost when three‐week intervals were used.

ISSN:0143-6147    

DOI:10.1080/09670878609371045

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effects of cuitivar, time and amount ofChilo partellusSwinhoe infestation on sorghum yield components were investigated. Damage to plants was greater on young plants with higher levels of infestation. Secondary tiller production was influenced by damage to primary tillers, which was related to the time and amount of infestation. The time of infestation was critical for panicle production and young plants in the vegetative phases were the most affected. The total grain yields were reduced in the infested plants and the extent was dependent on the cuitivar, time and level of infestation. Plants with more infestation at the young stages of growth showed the most yield reduction, which was caused by reduced numbers and weights of primary tillers and by the secondary tillers produced being less effective. The implications of these findings for the management of the pest are discussed.

ISSN:0143-6147    

DOI:10.1080/09670878609371046

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Two tests were conducted to evaluate certain chemicals againstMicrotermes najdensisHarris when applied one week after or 5 days before transplanting green pepper. Treatment of the soil before transplanting proved more effective for damage suppression than after transplanting. The maximum reduction percentages over the check obtained in both cases were 21 and 31% respectively. Out of 10 formulations applied in both tests, dieldrin (20% e.c.) at the rate of 3 kg a.i./ha, chlordane (72% e.c.) at the rate of 2%, Scidco PLS† (diluted with water 1 : 10) and chloropy‐riphos T.C. (42% e.c.) at the rate of 1 litre/100 litre of water/ha were the best chemicals used against this pest. Damage percentages of about 8, 9, 6 and 7 were recorded for the above mentioned chemicals respectively; the differences between them not being statistically significant. The use of both dieldrin and chlordane has been now prohibited in Saudi Arabia, due to their high persistence and toxicity, and Scidco PLS and chloropyriphos T.C. are considered the best less‐toxic and safer alternatives.

ISSN:0143-6147    

DOI:10.1080/09670878609371047

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Studies were conducted to determine the economic threshold of whitefiy,Bemisia tabaciGenn. on cotton at the Cotton Research Station, Muktsar during 1981 to 1983. The results show that the spray on American cotton var LH 372/F 414 against whitefiy be initiated as and when a population of 6 to 8 whitefiy adults/leaf is noticed from mid July onwards or when the middle canopy leaves show yellow spots and are sticky by touch. The average reduction in yield due to whitefiy attack were 8% and 10% in the first and last years and 31% the maximum in 1982–83.

ISSN:0143-6147    

DOI:10.1080/09670878609371048

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor