摘要:

The use of biodegradable, controlled release, cellophane bags for pest and disease control and fertilizer application in watermelon (Citrullus vulgaris) in Brunei is described. The bags are made of a microperforated nitrocellulose-coated cellulose film which biodegrades completely in three to six months depending on environmental conditions and the thickness of the bag. Two trials (1979 and 1980) with seven replicates were carried out. Fertilizers and chemicals were placed in bags and buried in the middle of the plots, or they were applied in the standard way as soil dressings and sprays. A control plot had no fertilizer or chemical application. Results of the 1979 trial showed no significant differences between treatments even though control plots had a lower number of harvested fruits. In 1980 there was a significant difference between the two treatments and the control. Considerable labour costs are saved using the bags and they have a potential use in many crops.

ISSN:0143-6147    

DOI:10.1080/09670878109413824

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Sweet potato vein clearing disease agents have been eliminated from 20 elite clones of sweet potato through meristem tip culture. Meristem tips of 0.25 to 0.4 mm length were cultured in a modified Murashige and Skoog medium. Plantlets were obtained after two months and transferred to soil. Indexing was accomplished by approach grafting toIpomoea setosa. About 80% of the plants obtained by meristem tip culture indexed negatively. Rapid multiplication was accomplished using single node cuttingin vitro. A multiplication rate of 4.2 /month was obtained. The material can be stored in tissue culture for one year without transfer to fresh medium. Virus-free material of IITA elite clones of sweet potato is available for distribution.

ISSN:0143-6147    

DOI:10.1080/09670878109413825

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

In a commercial planting of onion, root and basal rots reduced establishment of sets to 44%, which with 30% basal rot in harvested bulbs, represented an overall numerical loss of potential yield of 69%.Fusarium oxysporum, already present in sets at planting, contributed to poor establishment. Isolation from seedlings grown for sets in virgin soil at three locations yielded infection rates of 80 to 90%. In two field trials to evaluate fungicide treatments mean establishment was 47%. In the first trial involving dusting of the sets before planting Granosan 200 (benomyl 15% + mancozeb 60%) increased establishment by 28%, reduced basal rot of harvested bulbs by 77% and increased yield by 106%. Benomyl decreased basal rot and increased yields but captan and thiram treatments were ineffective. When bulbs from this trial were stored for six weeks under ambient conditions losses were 94% in controls and 45% in the benomyl + mancozeb treatment, with losses from other treatments intermediate. In the second trial, using pre-planting dips of benomyl the optimum concentration/time of 100 μ/ml for 15 min, reduced basal rot by 65% and increased yield 54%.

ISSN:0143-6147    

DOI:10.1080/09670878109413826

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

An intensive survey of cultivated plants throughout the island of Montserrat resulted in the identification of a number of viruses. Squash mosaic virus was found in cantaloupe, pumpkin and squash. There were cases of multiple infection of pumpkin and squash by cucumber and squash mosaic viruses. Potato virus Y was recovered from pepper and tomato. Bean yellow mosaic and cowpea mosaic viruses were found in red kidney bean and string bean while cowpea mosaic virus was found in cowpea and broad bean (Jamaica bean). Other viruses that were previously identified on the basis of field symptomatology were confirmed by host range and serology. Viruses were not recovered from sea island cotton or from sweet potato, although field symptoms on the sweet potato are similar to those caused by sweet potato mosaic virus. The leaf tissues of crop plants were inoculated to a wide range of indicator plants. Some of those that reacted systemically were examined by electron microscopy for virus particles and the sap extracted from them was used in serodiagnostic assays for virus identification. This is the first attempt to identify positively the viruses of crop plants on the island.

ISSN:0143-6147    

DOI:10.1080/09670878109413827

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Herbicides were evaluated for selective weed control in pearl millet in field trials conducted in the Sudan and the Northern Guinea zones of Nigeria from 1977 to 1979. Some of the herbicide treatments had a supplementary weeding, during the two later years of the study. The work was extended to the Southern Guinea zone in 1979. Propazine at 0.8 kg a.i./ha was the most tolerated herbicide on the loamy sand soils of the Sudan zone. It was tolerated up to 1.6 kg a.i./ha in the comparatively heavier sandy loam soils of the Guinea zones. Linuron was toxic to the crop at equivalent rates. Mixtures (1:1) of the two herbicides were better tolerated than linuron alone but did not show any advantage over propazine. The selectivity of terbuthylazine, used in one out of three years, was comparable in the Northern and Southern Guinea zones while it was less selective in the Sudan zone. Under severe weed infestation, one supplementary weeding following pre-emergence herbicides resulted in yields comparable to those obtained with two hoe-weedings. An average loss of 46% in grain yield was caused by unchecked weed growth.

ISSN:0143-6147    

DOI:10.1080/09670878109413828

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Plots 17 × 5 m were laid out in farmers' fields in three villages. Treatments (replicated thrice) included atrazine (0.5 or 1.0 kg a.i./ha) on sorghum and nitrofen (0.75 and 1.5 kg a.i./ha) on groundnuts with or without hand-weeding or farmers normal weed control. Groundnuts were unfertilized, sorghum received 20 or 80 kg N/ha. Cooperating farmers were allocated plots for traditional weed control, other operations were carried out by research staff. Some plots were discounted because farmers withdrew cooperation or did not participate correctly or because of flooding. In groundnuts nitrofen alone was inferior to nitrofen + one hand-weeding. In sorghum there were no differences between high and low fertilizer regimes. Atrazine gave superior yields to farmers' weed control. All treatments were better than the unweeded control. Generally farmers fields had low weed populations due to good, timely control and low soil fertility. Herbicides are not economic at present. Problems associated with research in farmers fields included: selection of farmers who would participate correctly, variability between different farmers' weeding practices and between different fields due to previous crops and cultural practices; lack of control of farmers weeding operations and the distance of experimental plots from the research station. The authors suggest that small experiments with only 4-6 treatments are easier for participating farmers to comprehend, selecting suitable size and shape of plots is important and that if many farmers are involved the number of replicates can be reduced.

ISSN:0143-6147    

DOI:10.1080/09670878109413829

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Insect pests, other arthropods and rodents causing damage on cassava crops in south India are listed comprehensively with nine photographs. Information is given on their distribution, nature of damage, economic importance and control measures. Twenty three species of pests attack cassava in the field and of these 17 are first records on cassava. Although several cause damage, tetranychid mites and rodents can be classified as ‘key’ pests of cassava in India. Future research strategies should be directed towards the development and use of resistant varieties, biological control, improved agronomical and management practices, including judicious use of mineral fertilizers.

ISSN:0143-6147    

DOI:10.1080/09670878109413830

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Penfluron and diflubenzuron, both chitin synthesis inhibitors known to be highly effective against nymphs ofPoekilocerus pictus(F.), were tested against the adult for their possible effects upon reproduction. These compounds were found to have the maximum effect, when no eggs were laid, if both sexes were treated. The eggs of treated males × untreated females did not hatch and those of treated females × untreated males gave rise to nymphs which died before reaching maturity.

ISSN:0143-6147    

DOI:10.1080/09670878109413831

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A continuing research programme of chemical control on major cotton pests in Thailand has been conducted since 1960 to discover the most effective insecticides. Before 1978 twelve systemic insecticides for controlling the cotton leafhopper,Amrasca devastans(Dist.), and the cotton aphid,Aphisgossypii Glov., and eight insecticides for controlling the cotton bollworm,Heliothis armigera(Hbn.), were identified and sent for official recommendation. This report gives details of research work carried out during 1978 and 1979, and includes seven new compounds, decamethrin, cypermethrin plus amitraz, sulprofos, profenofos, profenofos plus DDT, thiofanox and thiodicarb RH 0994, for bollworm control. The bollworm resistance to synthetic pyrethroids and the increase in whitefly,Bemisia tabaci(Genn.), after using the synthetic pyrethroids are also discussed.

ISSN:0143-6147    

DOI:10.1080/09670878109413832

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

An investigation of the downwind movement, distribution and distance covered from a spray source of insecticide to which oil is an additive. Vertical targets were placed at distances ranging from 0.25 to 64 m and at three heights, 35, 70 and 150 cm, downwind from the spray source. There was an increase in the number of droplets arriving at the targets when 20% oil was added to the aqueous solution. An even greater increase was seen when oil only was sprayed; these results are compared with sprays containing water and a 5% wetting agent. Droplet size and air turbulence effects are discussed, as is the faster evaporation of water-based sprays. The work was carried out on rhododendron leaves using Saturn yellow fluorescent dye as a tracer using a Micron Mini-ULVA and Ulvapron oil. A comparison is made with the use of Shell oil A and Risella 33 used by pest workers.

ISSN:0143-6147    

DOI:10.1080/09670878109413833

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor