摘要:

In 2‐year field trials with three different copper formulations it was observed that the incidence of bacterial blight of coffee decreased in response to increasing amounts of copper in sprays. However, reduction of disease achieved by the sprays was not in proportion to the amount of copper in each formulation. Similar sprays of each of the three formulations achieved different levels of blight reduction in different sites. The sprays became less effective as bacterial blight infection pressure increased. The dual effect of these sprays on the control of coffee berry disease was also limited by the copper content in the sprays. The interaction of copper formulation, dosage and site factors in the control of bacterial blight, coffee berry disease and yield response are discussed.

ISSN:0143-6147    

DOI:10.1080/09670879109371526

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Seventy species of insects were found on potato; 52 of them were pests and 17 were predators of those pests. Their importance as pests and predators is discussed.

ISSN:0143-6147    

DOI:10.1080/09670879109371527

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670879109371528

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Large‐scale field trials conducted inthreegovernorates in Egypt during the 1987 cotton season showed that two or three applications of pink boilworm pheromone (formulated as either microcapsules or hollow fibres) integrated with one or two applications of conventional insecticides gave as good a control of bollworms as did four or five applications of the insecticides alone. Estimated yields per feddan in two governorates, Fayoum and Dakahlia, averaged from 998 to 2164 kg in the pheromone‐treated blocks compared to 1076 and 1628 kg in the insecticide‐treated control blocks. While no significant differences in yields were detectable in the Fayoum, an increase of up to 17% in seed cotton weight was estimated in the pheromone‐treated fields in Dakahlia. This increase in yield was attributed to enhanced hybrid vigour as a result of introducing beehives into the pheromone‐treated fields during the early stages of flowering and fruit setting. The bees, in addition to cross‐pollinating the cotton flowers, produced over 10 metric tonnes of honey. These excellent results were obtained in spite of a general increase in pink boilworm infestation throughout the governorate as deduced by a comparison of green boll infestation between 1986 and 1987. The results by a comparison of green boll infestation between 1986 and 1987. The results also underlined the importance of early season pheromone treatments, since the treatments at Dakahlia went on at an earlier stage of crop development than in either Kafr El Sheikh or Fayoum.

ISSN:0143-6147    

DOI:10.1080/09670879109371529

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Diaphania indicaSaunders larvae feed on cucumber leaves, almost defoliating plants when populations are high. Using insecticide treatments, population levels of caterpillars were manipulated in cucumber plantings. Carbaryl, dimethoate andBacillus thuringiensiswere effective in reducing caterpillar populations. Regression analysis of yield of cucumbers onD. indicapopulations per leaf showed that yield loss was approximately 10% whenD. indicapopulations reached one per leaf. Yield loss could not be detected below this level. Yield loss increased linearly as populations increased above 1 per leaf. Moderate populations ofThrips palmiKarny, up to 80 thrips per leaf, in one of the three trials had no significant effect on yield.

ISSN:0143-6147    

DOI:10.1080/09670879109371530

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Four maize lines, Mp78:518 (resistant), P47S3 (intermediate to susceptible), Tz3 and Ki3 (susceptible), and three experimental hybrids, P47S3 × Mp78:518 (resistant), Tz3 × Ki3 and Ki3 × T×601 (susceptible), were Infested with 15, 30, 45 and 60 southwestern corn borer (SWCB) larvae per plant at the 6–7 fully extended leaf stage. There was a small linear increase in leaf feeding ratings on resistant genotypes (Mp78:518 and P47S3 × Mpρ78:518) as the number of larvae increased. On susceptible genotypes leaf feeding increased sharply at 30 larvae when compared to 15 larvae. Additional larvae resulted in little change as the ratings at 30 larvae on susceptible genotypes were in the upper limit of the scale. Leaf feeding was significantly less on resistant than on susceptible genotypes. Neither plant height nor yield of resistant genotypes was reduced significantly (? = 0.05) at any infestation level. The results indicate that infestation with 15 larvae per plant gives low damage ratings and does not adequately partition the genotypes into resistant or susceptible. Because the components of resistance were identified precisely with 45 larvae per plant, and remained unchanged with additional larvae, the results indicate that artificial infestation with 45 larvae per plant is adequate for first‐generation SWCB resistance screening under field conditions in Mexico.

ISSN:0143-6147    

DOI:10.1080/09670879109371531

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Indian mustard(Brassica juncea(L.) Czern.) was found to be a preferred host for oviposition by diamondback moth,Plutella xylostella(Linnaeus) and leafwebber,Crocidolomia binotalisZeller as compared to cabbage(Brassica oleraceavar.capitataL.) in laboratory studies. Three field trials with different planting patterns of both cabbage and mustard were conducted to investigate whether mustard could act as a trap crop. Results revealed that cabbage grown alone supported significantly higher larval populations of both the pests as compared to mustard intercropped cabbages, and resulted in loss of marketability. It was also inferred that a planting pattern of 15 rows cabbage followed by mustard rows was found to be the most promising for successful management of both pests. Mustard was sprayed with 0.1% dichlorvos at 10‐day intervals commencing from 12 days after sowing to control insects that colonized it. Results also indicated that intercropped cabbages could be successfully raised during the rainy season without insecticidal application, while two sprays with 0.05% cartap hydrochloride was necessary during winter.

ISSN:0143-6147    

DOI:10.1080/09670879109371532

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Various species of ticks collected from different regions of Tanzania were tested for susceptibility to organochlorine (OC) acaricides between 1976 and 1987 using gamma HCH (lindane) and dieldrin as standard test chemicals. Of 189 strains tested, 85 (45%) had developed resistance to these chemicals, viz.Boophilusspecies (36.5%),Rhipicephalus appendiculatus(3.5%),R. evertsi(41.2%) andAmblyomma variegatum(3.5%). In an earlier survey carried out between 1973 and 1976, resistance was found in the following number of strains:R. appendiculatus(1),R. evertsi(3) andA. variegatum(1);Boophilusspecies were found to be resistant countrywide. Although the current survey indicates a marked increase in resistance, OC‐resistantR. appendiculatusthe sole vector of East Coast fever of cattle, still exists in the Kagera Region only. OC acaricides could therefore continue to be used for tick control on indigenousBos indicuscattle in all regions of Tanzania where resistant R.appendiculatusis not present.

ISSN:0143-6147    

DOI:10.1080/09670879109371533

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The efficacy of four pheromone‐trap designs was compared for catching male tobacco caterpillar,Spodoptera litura(F), moths in groundnut fields. There was no significant difference in the performance of the single‐ and double‐funnel traps, and the single‐funnel (20 cm dia) trap captured more moths than any other trap. Septa of 4 weeks or less exposure attracted most moths. One and two traps ha−1caught significantly fewer moths than four and more traps ha−1however there was no significant improvement in capture when four or more traps ha−1were installed. Night observations indicated that many moths escaped from sleeve traps. Single plastic funnel traps were found suitable and are being used in monitoringS. liturain the national monitoring network in India.

ISSN:0143-6147    

DOI:10.1080/09670879109371534

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The biology and control of the Asian corn borer,Ostrinia furnacalisGuenée, is reviewed. This insect is distributed from China to Australia and the Solomon Islands. In northern parts of its range the moths have one or a few generations per year, but in the tropics, generations are continuous and overlapping. The caterpillars can cause severe yield losses in corn, both by damage to the kernels and by feeding on the tassels, leaves, and stalks. Survival and growth of the caterpillar is highest on the reproductive parts of the plant. Other economic plants attacked include bell pepper, ginger and sorghum. Recently, the Asian corn borer appears to have become an important pest of cotton. A number of wild grasses are also used as hosts. Information on predators and parasites is summarized. Egg parasitoids are relatively effective in some tropical areas, but no significant larval or pupal parasites have been found. In temperate parts of the Asian corn borer's range, larval parasites are more abundant, having their greatest impact during the diapausing generation. A variety of techniques have been used to control the borer. Insecticides are used in many countries, but are not totally reliable. Augmentative release of egg parasitoids is widely used in China and has been tested elsewhere. Mechanical removal of the tassels can reduce borer populations 50%, and this procedure is used in the Philippines. Field corn varieties which are relatively resistant to the ACB have also been found.

ISSN:0143-6147    

DOI:10.1080/09670879109371535

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor