摘要:

In a series of four trials on sweet potato (Ipomoea batatas(L.) Lam.) four parameters relating to sweetpotato weevil(Cylas formicariusFab.) population and damage levels were recorded. These were the numbers of adult weevils per m2of foliage, the numbers of weevil life stages in 15 cm vine sections immediately above the tubers, the percentage of damaged vines and the percentage of damaged tubers. Strong positive correlations were found between the various parameters. Infestations of vines by weevils reduced the vigour of surface foliage and resulted in reduced yields. It was not possible to establish a spray threshold because reduced yields and damage to tubers occurred at low population levels. The number of rainy days between 60–90 days from planting was negatively correlated with the percentage of damaged tubers at 175 days from planting.

ISSN:0143-6147    

DOI:10.1080/09670878609371085

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Insect growth regulators (IGRs) Ro 20–3600 and MV‐678 were found to be ineffective to adults of the rice weevil,Sitophilus oryzae(L.), via wheat treatment. On the other hand, the two IGRs and another IGR, R‐20458 were very effective by direct contact, e.g., the IGR MV‐678 caused 100% mortality at 20 ppm (v/v) dosage applied topically to pupae of the rice weevil. The mode of action was apparently similar for all the IGRs tested, however, they differed in relative potency.

ISSN:0143-6147    

DOI:10.1080/09670878609371086

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The population of insects on the soyabean crop was estimated from catches in a standard sweepnet from the upper canopy in the field two times a week beginning at the early vegetative stage up to maturity. The highest peaks ofAbidama productaWalk andCafnasp. were found in the beginning of stage V1; those ofSogatella furciferaHorvath,Adonia variagata, Afidenta mimetica simplexOke,Coccinella septempunctataL.,Haltica birmanensisJac.,Heterodeses lenisCand.,Ophionae indicaThnbg.,Phillotretasp.,Piatypria histrixF.,Popillia cupricolisHope,Scatophaga stercorariaL.,Meteorusnr.fragilisWesm.,Paedarus fuscipesCurtis at the vegetative stage (V2), andNephotettix nigropictusStall.,Paratettixspp.,Monolepta signata01. andMonoleptaspp. at stage V4. The populations ofAethus indicusWest and ofCydmus aterrimusF. reached three peaks in (V1), (V4) and (V6) respectively. During the reproductive stages,Tipula melanomeraWalk.,Chauliops fallaxScott.,Graptostethus servusFab.,Lygus pretensisL.Lygusspp.,Nysiussp.,Acridasp.,Attractomorphasp.,Oxyasp., andPhaneroptera gracilisBurn were active at R1‐R2stages butLycosasp.,Oxyopessp., andTetragnathasp. at R1‐R2and R4stages, followed byEurydama pulchrumWestwood,Menido histrio, Nezara antenataScott.,Nezara viridulaL.,Nezaraspp., at the seed formation stage (R5). The time of the reproductive stage of the soyabean

ISSN:0143-6147    

DOI:10.1080/09670878609371087

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The agromyzid leafminerLiriomyza trifolil(Burgess) was accidentally introduced to Guam in the late 1970s, resulting in serious crop losses to fresh pole beans and yard‐long beans. A series of insecticide tests showed that none of the chemicals in use on beans controlled the leafminer to any significant extent. However, synthetic pyrethroids provided excellent control. The most common parasites found wereHemiptarsenus semialbiclavusGirault andChrysonotomyia formosa(Crawford). Fenvalerate was not found to have a significantly deleterious effect on the number of these parasites found in bean leaves. A strong correlation between the number of mines per leaflet and the yield was observed in yard‐long beans. Yields declined rapidly as the seasonal mean number of mines per leaflet increased from 5 to 15 but declined less rapidly at higher numbers, reaching a minimum non‐zero level when the leaves were completely consumed by the miners.

ISSN:0143-6147    

DOI:10.1080/09670878609371088

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Experiments were conducted to find out suitable pesticides, dose and method of application to control white grubs (Scarabid beetles) damaging sugarcane in northern and northwestern districts of Bangladesh. Pesticides tested were Dieldrin (50WP, 40WP, 20EC), Heptachlor (40WP, 20G), Aldrin 5D, Ekalux 5G (Quinalphos) and Furadan 3G (Carbofuran) at varying doses and methods. Furadan 3G at 2.0 kg a.i./ha and 1.5 kg a.i./ha and Ekalux 5G at 2.0 kg a.i./ha significantly controlled white grubs. The yield following Furadan 3G at 2.0 kg a.i./ha was quite profitable in sandy and poor soils that were also affected by nematodes. Other pesticides belonging to chlorinated hydrocarbon groups were ineffective on grubs and sugarcane yield.

ISSN:0143-6147    

DOI:10.1080/09670878609371089

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Studies were conducted during May 1984 on estimation of losses in okra under field conditions naturally infested withMeloidogyne javanica.The yield of okra was reduced at population levels of 296 ± 5Meloidogyne javanicalarvae per 250 g soil. Percentage avoidable losses in yield ranged from 20.2 to 41.2% by using carbofuran and aldicarb at 2.0 and 4.0 kg. a.i./ha respectively. Aldicarb gave better results than carbofuran at both the doses. Cost‐benefit ratio was found maximum (1:11.7) with aldicarb at 2.0 kg a.i./ha whereas it was minimum (1:1–8) in carbofuran treated plots at 4.0 kg a.i./ha.

ISSN:0143-6147    

DOI:10.1080/09670878609371090

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The level of infestation by the shoot borer(Dichocrocis punctiferalisGuen.) that results in a significant reduction in yield of ginger rhizomes has been evaluated; these levels are 60, 45 and 50% of pseudostems damaged per plant during August, September and October respectively. The Economic injury Level has also been worked out and a sequential sampling scheme developed for monitoring the level of pest infestation in the field as a guide for undertaking control measures against the pest.

ISSN:0143-6147    

DOI:10.1080/09670878609371091

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A field evaluation was made of 14 cultivars (11 Ghanaian and three exotic) ofSolarium melongenato infestation byLeucinodes orbonalis.Infestation of both shoots and fruits of all cultivars increased steadily during the experimental period. Shoot infestation was significantly highest in the cultivar Nyadoahene and least in Pakro Special, Kwadaso 3C and Florida Market. Fruit infestation was also significantly highest in Nyadoahene. Fruits of the cultivars Black Beauty and Florida Market were significantly least infested. Florida Market showed the most resistance to the insect with respect to both shoot and fruit infestations. The cultivars Kwawu Ntrowa, Gaab, Danso II, Pakro 5, Odwanhwoa, and Pakro Special 5C (in that order) were the least resistant to shoot infestation, while Nyadoahene, Danso II, Gaab, Kwawu Ntrowa, Odwanhwoa, and Pakro 5 (in that order) showed the least resistance to fruit infestation. In general, the Ghanaian cultivars were more severely infested byL. orbonalisespecially in the case of fruit infestation.

ISSN:0143-6147    

DOI:10.1080/09670878609371092

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670878609371093

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670878609371094

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor