摘要:

The nature and extent of the environmental effects of insecticides applied in tsetse control/eradication operations depend on the actual insecticide used and the mode of application. A comparison of the impact of insecticides with that of previous control methods, e.g. bush clearing and game destruction, shows that the latter produce a greater impact. Rural development, which is not necessarily dependent on tsetse eradication, also produces environmental changes, and the impact of tsetse control/eradication by insecticide application should not be considered in isolation.

ISSN:0143-6147    

DOI:10.1080/09670878009414405

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Abundance of termites, damage to plants and loss in yield were studied on recently-cultivated and long-cultivated fields at Mokwa in the southern Guinea savannah zone of Nigeria. Virtually all damage was caused byMicrotermeswhich have deep, diffuse subterranean nests and attack maize by entering the roots or prop-roots and may eventually extend their foraging by excavating the stem to heights varying from a few centimetres to over a metre. Attack on the roots commences at 10 to 12 weeks after planting and intensifies as the plants mature. Attacked plants may remain standing or fall over (lodged). Yield of grain on standing attacked plants was not significantly different from yield on standing unattacked plants. Cobs of lodged plants were damaged on the ground by termites, ants, rodents and pathogens and yield of grain was significantly lower than on standing plants. Yield losses on recently-cultivated fields (1–3 years) varied from 0.1 to 3.0% and on long-cultivated fields (10–27 years) from 3.9 to 9.5%. Abundance ofMicrotermesincreased from 877/m2in the first year of cultivation to 2997/m2after 3 years; on the long-cultivated plots abundance was approximately 4000/m2. Damage (% lodging) and loss in yield were linearly correlated with abundance ofMicrotermesand years of cultivation.

ISSN:0143-6147    

DOI:10.1080/09670878009414406

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Seasonal incidence of shootfly,Atherigona naqviiSteyskal was studied in wheat sown on nine dates at approximately fortnightly intervals from 1 October to end of January during the 1973–74 to 1976–77 seasons at Jaipur, India. During the season the pest remained more active from the second fortnight of October to mid-December and again during February and March. These fluctuations appear to have a positive correlation with maximum and minimum temperatures while relative humidity and rainfall did not have any influence. The winter low temperatures during mid-December to mid-February arrested the flies' activity. The crop sown between mid-November and mid-December was found to be almost free from shootfly and no control measures are needed. However, early and late sown crops remained prone to attack.

ISSN:0143-6147    

DOI:10.1080/09670878009414407

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A total of 13 species of shootflies from two genera,AtherigonaandAcritochaeta, were reared over a four-year period from a range of sorghum (Sorghum bicolor) cultivars showing typical ‘dead heart’ symptoms.Atherigona soccataRond. was the dominant species (<99% of the flies reared), while the second most common species wasAcritochaeta orientalisSchin. An interesting record wasAtherigona eriochloaeMall. reared from tillers of ratooned sorghum. Three species as yet undescribed were recorded. More females than males were reared in the course of the study — the sex ratio was 1:1.27. It was concluded that onlyA. soccatais likely to be important when considering control of damage to sorghum by resistance breeding or the use of insecticides.

ISSN:0143-6147    

DOI:10.1080/09670878009414408

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The main pulse crop during the kharif season in Uttar Pradesh (India) is pigeon pea.Melanagromyza obtusaMalloch,Exelastis atomosaW.,Heliothis armigeraHubn.,Euchrysops cnejusFab.,Maruca testulalisGeyer andAnarsia ephippiasMeyrick are the important pod borers which cause great damage to this pulse crop. The symptoms of attack and methods of pest control are described.

ISSN:0143-6147    

DOI:10.1080/09670878009414409

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The cassava breeding materials from the International Institute of Tropical Agriculture (IITA) were evaluated for resistance to cassava green mite (CGM) at the Chambesi and Kizimbani Stations, Tanzania, where CGM population was high. At Chambesi Station, 58 clones (15%) of the 377 clones tested under natural infestation were rated resistant (classes 1 and 2) to CGM. In Zanzibar the CGM-resistant clones, which were high yielding, resistant to cassava mosaic disease (CMD) and acceptable in consumer quality, are being multiplied for distribution to farmers.

ISSN:0143-6147    

DOI:10.1080/09670878009414410

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

First instar larvae ofHeliothis armigerawere marked with rain-resistant ink and released on field-grown cotton plants. The larvae were monitored through to the fifth (final) instar stage while recording information on feeding, distribution, exposure and movements. The results obtained embody the first, comprehensive account of the behaviour ofHeliothis armigeraas the most important insect pest of cotton in Thailand. The development of a simple scouting technique based on these findings and using first and second instars only is discussed.

ISSN:0143-6147    

DOI:10.1080/09670878009414411

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Cassava bacterial blight (CBB) is a major problem of cassava in Uganda. It was first recorded in Terego County, Nile Province in 1976, and a disease survey indicated that CBB is now present in over half of the country. Losses of 90–100% have been observed on susceptible varieties in parts of the Nile, North and Eastern provinces. Symptoms include angular leaf spots, blight, wilt dieback and gum exudations. Planting of infected materials, rainfall, hailstorms, wind and insects are major factors in the spread of the disease. Restriction of movement of infected cassava cuttings to non-infected areas, planting of resistant varieties and healthy cuttings, encouragement of mixed cropping and crop rotation are recommended for control.

ISSN:0143-6147    

DOI:10.1080/09670878009414412

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The role of seed and pollen in the spread of pathogens is discussed. With the exception of mycoplasmas all other groups of pathogens can be seed transmitted. It is important to understand where and how the pathogen is located in the seed and examples are given of how various pathogens are transmitted. Storage of seed may reduce but not eliminate inoculum of important pathogens. Pollen provides a valuable tool for crop improvement but exchange of pollen risks introducing plant pathogens into new areas. A number of viruses, as well as a few bacteria and fungi, are pollen transmitted. Seed inspection and health tests are important for the detection of seed-borne pathogens. Some of the tests used are described.

ISSN:0143-6147    

DOI:10.1080/09670878009414413

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Several fungicides, antibiotics, oils and oil cake extracts were tested for their effectiveness against sugarcane downy mildew of maize caused bySclerospora sacchari. In the laboratory eight fungicides, three oils and two oil cake extracts significantly inhibited conidial germination. In the field seed treatments with chloroneb, toluene-p-sulphonamide and sodium lauryl sulphate significantly reduced disease incidence. Furrow treatment with chloroneb gave better results than the seed treatment. In the glasshouse azadirachta and maduca oils and extracts of their cakes gave promising results. A combination of chloroneb seed treatment, rogueing of infected plants and one foliar spray of azadirachta oil gave the most effective control.

ISSN:0143-6147    

DOI:10.1080/09670878009414414

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor