摘要:

Two hundred and one rice cultivars bred at Central Rice Research Institute (CRRI) were evaluated for tungro resistance by field screening technique. Fourteen rice cultivars were identified as field resistant. Based on field evaluation trial and greenhouse reaction, the rice cultivars CR146–7003, CR 260–131–5–713, CR 260–136–321 and CR 319–644 had high degree of resistance to tungro with high yielding ability. These cultivars are being tested in multi‐locational trials for their suitability under different agroclimatic conditions in various parts of India. Eighteen hundred cultivars bred by breeders in different states of India were field evaluated for tungro resistance. Nine cultivars were rated as highly resistant to tungro under field conditions. Out of 70 multiple resistant varieties tested, a bacterial leaf blight resistant variety BJ 1 had a high degree of resistance to tungro also.

ISSN:0143-6147    

DOI:10.1080/09670878909371318

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The efficacy of four granular insecticides, carbofuran, bendiocarb, BPMC, and isoprocarb were assessed for tungro prevention and its control by root zone application method. All these insecticides were proved to be similar in persistency in greenhouse tests up to 37 days after treatment showing both in preventing tungro infection and causing vector mortality. In field tests using two rice cultivars, Taichung (Native) 1 and Ratna, carbofuran as root zone application was found to be much superior to broadcast application. There was no significant difference between 1 and 2 kg a.i./ha. The effects of bendiocarb, BPMC and isoprocarb as root zone application were almost similar to broadcast application of carbofuran.

ISSN:0143-6147    

DOI:10.1080/09670878909371319

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

To develop a multivariate model for predicting yield data were collected in farmers’ sorghum fields where gray leaf spot, smut, rust, and oval leaf spot epidemics occurred in 1985. Several models were tested to explain variation in yield based on a range of variables measured on individual plants. Data were first subjected to principal component analysis, and the major principal components were used as independent variables in a multiple regression model, with yield the dependent variable. The best model included the following variables: per cent severity of the 4 diseases, panicle length, and plant height. Using the model, yield differences of up to 7% were predicted when comparing the minimum‐ and the maximum‐disease severities observed and holding plant height and panicle length at their mean values. Using the observed plant height and panicle length corresponding to actual disease severities, yield differences estimated were 14.6%, 3.6%, and 5.5% for gray leaf spot, rust, and oval leaf spot, respectively. Actual losses from smut were insignificant.

ISSN:0143-6147    

DOI:10.1080/09670878909371320

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The persistence of water based (e.c.) and oil based (u.l.v.) formulations of endosulfan was compared by chemical and bio‐assay. A rapid rate of decay occurred with the e.c. formulation in the first 24 hours after which it declined to a rate similar to that followed by the u.l.v. formulation from the outset. The higher initial loss with the e.c. product resulted in about half the leaf residue in comparison to the u.l.v. formulation at a given point in time, with consequently more prolonged control ofHeliothislarvae with the u.l.v. formulation.

ISSN:0143-6147    

DOI:10.1080/09670878909371321

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A new technique (mature aerosol placement) enables single drops of insecticide aerosols to be applied to individual insects. Monodisperse drops are generated in a wind tunnel, collected on silk threads and transferred to the test insects. The technique has been used with tsetse flies and u.l.v. formulations of synthetic pyrethroids.

ISSN:0143-6147    

DOI:10.1080/09670878909371322

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Five species of rodents, viz.,Bandicota bengalensis wardi(Wroughton), Musplatythrix(Thomas),M. musculus(Linnaeus),M. booduga(Gray) andM. cervicolor(Hodgeson), have been recorded from the area under investigation with a per cent occurrence of 43.65, 16.48, 19.65, 14.52 and 5.7 respectively. The fluctuation of murid population in the field during different months of the year seems to be due to some biotic and abiotic factors, the consideration of temperature, food, shelter and breeding period being important. Involvement of people and the constraints in rodent control operation have been investigated. It is revealed that there is a general apathy towards the control of rodents on account of (i) religious beliefs and teachings, (ii) additional labour and time factor, and (iii) economical factor. The farmers would catch and release the rodents at some distant place rather than kill them. Since women generally tend to agricultural field work, they do not want to have any additional burden such as treatment of burrows. Even those fanners who are interested in rodent control get disillusioned with the programme because they cannot get genuine rodenticides at reasonable rates. However, result‐oriented training and demonstration of experiments, made a fairly large number of people interested in rat control. The role of university and social groups in propagating the rat control campaign in the area besides the official distribution/ sales centres for rodenticides has been discussed.

ISSN:0143-6147    

DOI:10.1080/09670878909371323

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The seasonal occurrence of the earhead bugCalocoris angustatusLeth. (Hemiptera: Miridae) in main and ratoon crops of two sorghum hybrids was studied in field experiments with fortnightly sowings. During April to June, 1984, early April sowings were severely infested and early June sowings had less infestation. Hybrid CSH 5 harboured more bug population than the other. A ratoon crop had a lower population than the main crop. In July to October, 1984, the crop sown in the first fortnight of September had the lowest population of 18 bugs per ten panicles and a higher population of 142–159 bugs in July sown crops. The main crop had a higher population in all the sowings with an average of 116 bugs per ten panicles whereas the ratoons of September and October had no infestation, a mean of 7 bugs per ten panicles. A third experiment sown during January to March 1985 differed from the others by having a lower population in the main crop (22 bugs) than in ratoon (72 bugs/10 panicles). In the main crop, the January sown crop had no population and crops sown in February and March were little infested, whereas ratoon crops had a higher population than the main crop in all sowings. In general, crops sown in February and March first fortnight, had a higher population. In all the sowings, of the four stages of observation, pre‐flowering, milky, dough and maturity stages, the dough stage had the maximum population of bugs except in crops sown during February and March 1985, where the milky stage had the highest population. Cultivar CSH 5 was always more attacked than K‐Tall.

ISSN:0143-6147    

DOI:10.1080/09670878909371324

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The biology ofSylepta derogataFabricius was studied in the laboratory. The number of larval instars varied from 5 to 6 when fed singly. The larva possesses three pairs of thoracic legs and four abdominal prolegs. Among morphological differences between the instars, the most striking between the 1st and 2nd instars was the presence on the 2nd of two brown spots on the dorsal aspect of the prothoracic segments. Other instars were differentiated by the size and shape of the shields. The pupa is obtect and conical in shape with ten abdominal segmants, distinctly separated except the 9th and 10th segments. The genital pore occurs ventrally below the 8th abdominal segment in the female and in the male on the 9th segment. The abdomen of the male is more slender than that of the female. The life cycle was completed in 33.9 ± 0.5 days.

ISSN:0143-6147    

DOI:10.1080/09670878909371325

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Chemical, physical and biological treatments were tested against the coconut mite,Eriophyes guerreronisKeifer, the most serious arthropod pest of coconuts in St. Lucia and some neighbouring states. None of the treatments resulted in control of the pest which caused up to 31.5% loss of potential yield. The major scope for yield increases did not lie with mite control but rather in improved agronomic practices, which, if allied to replanting with improved and mite resistant cultures, could at least double present yields.

ISSN:0143-6147    

DOI:10.1080/09670878909371326

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Foliar pests of watermelon in Hawaii includeLiriomyza sativaeBlanchard andLiriomyza trifolii(Burgess) (Diptera: Agromyzidae),Thrips palmiKarny (Thysanoptera: Thripidae),Aphis gossypiiGlover (Homoptera: Aphididae),Tetranychus cinnabarinus(Boisduval) (Acari; Tetranychidae) andTrialeurodes vaporariorumWestwood (Homoptera: Aleurodidae). In studies in 43 commercial plantings arthropod pest densities remained below density treatment levels (DTLs) without weekly pesticide applications.T. palmiandA. gossypiiwere the major foliar pests on Oahu (1984–1985) and Molokai (1986) because DTLs were surpassed between 12 and 41 % of the survey dates. The occasionsT. palmiandA. gossypiisurpassed DTLs varied with locality and in the latter species with the presence of non‐persistent transmitted viruses.Liriomyzaspp.,T. cinnabarinusandT. vaporariorumdensities surpassed DTLs less than 11 % of the survey dates.

ISSN:0143-6147    

DOI:10.1080/09670878909371327

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor