摘要:

Adult pepper weevils,Anthonomus eugeniiCano, were more exposed and hence easier to count between 08.00 and 11.00 hours than at any other hour of the day. Twice weekly counts of exposed adult weevils and the use of action thresholds of either one or two adults per 100 terminals resulted in more cost effective control than did weekly scheduled applications. The former threshold is recommended for capital intensive farmers, while the latter may be most appropriate for capital‐limited producers. Manual collection and destruction of fallen fruits was not a cost effective supportive tactic where insecticides were used, but may be of limited value in the absence of chemical control. The low’ cost, simplicity and efficacy of the procedures described should make them acceptable to small scale, capital limited farmers.

ISSN:0143-6147    

DOI:10.1080/09670878609371017

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Nine sweet potato cultivars were grown on St. Croix, U.S. Virgin Islands and assessed for development of weevil populations. Of the two species present,Cylas formicarius elegantulus(Summers) was more numerous thanEuscepes postfasclatus(Fairmaire) (94%). All cultivars were infested soon after planting and populations became large enough to reduce yields. Ratios of the two species varied depending upon cultivar. Differences were observed in susceptibility among cultivars and were identified as escape, tolerance and nonpreference. In conjunction with other control strategies, sweet potato varieties that are less susceptible to weevil infestations will be useful in managing weevil populations in the tropics.

ISSN:0143-6147    

DOI:10.1080/09670878609371018

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Investigations into the biology and seasonal and specific variation of the most important pests(Cryptophlebiaspp. andNezaraspp.) of macadamia in Malawi are described. Details are given of the times taken for the eggs and larvae ofCryptophlebiaspp. to develop. The alternative hosts of both groups of pests are given.Cryptophlebialarvae are attacked in the nut by a number of parasites, which are listed and details of their frequency through the season are given. A maximum apparent parasitic percentage of 40% is recorded.Nezaraeggs are parasitized byTrissolcusspp. (Scelionidae), on average 74% of the eggs are parasitized. Nuts fed on byNezaramay develop infections by four fungi. The seasonal occurrence of the pests is given and the relationship of‐these with the susceptible stages of the crop is examined. The relationship of pest numbers with damage levels is investigated.

ISSN:0143-6147    

DOI:10.1080/09670878609371019

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An investigation was carried out on Jaya var. rice transplanted in the last week of June 1981–62 and 1982–83 to assess the most suitable growth stage for insecticidal treatment and to determine the avoidable losses caused by whitebacked plant hopper (WBPH)Sogatella furciferaHorv., at Rice Research Station, Kaul, Kurukshetra. Carbofuran 3 G at 1–25 kg a.i./ha during 1981–82 and phorate 10 G at 1.5 kg a.i./ha were applied at three growth stages at 5, 30 and 60 days after transplanting (d.a.t.) either once or with repeated doses at 5 + 30, 5 + 60, 30 + 60 and 5 + 30 + 60 d.a.t. Quinalphos 25 e.c. and monocrotophos 40 e.c. (Nuvacron) at 0.5 kg a.i./ha were applied as foliar spray at 50 and 80 d.a.t. in second and third stage protection respectively. Carbofuran alone or with repeated foliar sprays protected 7.5–23.3% grain losses whereas phorate alone or with combination repeated doses gave 13.9–30.6% increase in grain yield over unprotected check. The crop protected at the third stage (60 d.a.t. until harvest) invariably provided greater pest reduction and higher grain yield. The carbofuran treatments either alone or in combination did not prove economical whereas the net profit by the use of phorate alone or in repeated doses in different combinations ranged from Rs. 967.77–2298.38/ha. Phorate treatment at 60 d.a.t. followed by foliar spray with Nuvacron at 80 d.a.t. gave the highest return of Rs. 2298/ha and a cost/benefit ratio of 3.65. The average yield loss over two years was nearly 20%.

ISSN:0143-6147    

DOI:10.1080/09670878609371020

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Pod losses caused byCrinipellis perniciosa(Stahel) Singer passed 50% in cocoa plantings in their sixth year in Rondonia, Brazil where no control was applied. It is recommended that pruning should be initiated in the fourth year after planting. Recovery of fermentable seeds from diseased fruits was minimal, and pod losses could be used to estimate yield loss. Monthly losses had to be calculated by comparing actual harvests with predictions based on previous fruit set. Manipulation of harvest time by manual pollination may create difficulties with pod weight/ size and unpredictability of fruit wilt.

ISSN:0143-6147    

DOI:10.1080/09670878609371021

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Kernels of three maize varieties namely: Fraz 23, Fraz 34 and Bendel White planted in Eastern Nigeria in 1982 and 1983 planting seasons were screened for seed‐borne fungi. The effects of Thioral (a.i. 25% heptachlor and 25% TMTD), a biocidal seed‐dressing chemical, on seed‐borne fungi and on kernel viability were also investigated. Results showed that kernels of the three maize varieties screened harbouredFusarium moniliforme. Fusarium nivale, Fusarium semitectum, Aspergillius flavus. Penicillium oxalicum, Curvularia pallescens, Rhizopusspp. andSac‐charomycesspp. at appreciable high percentages.Fusariumspecies dominated the other fungi. These fungi caused appreciable reduction in the percentage kernels germinating. In Thioral‐treated kernels,F. moniliforme, F. Nivale, F. semitectum. P. oxalicum, C. pallescens, Rhizopus spp.andSaccharoymcesspp. were completely eliminated or reduced. The percentage kernel germination increased significantly(P= 0.001) and no phytotoxic effects were observed on the kernels’ seedlings treated with Thioral. The mean percentage incidence ofA. flavusisolated in Thioral‐treated kernels increased when compared with the untreated kernels in all the three maize varieties.

ISSN:0143-6147    

DOI:10.1080/09670878609371022

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Bravo 500EC and Difolatan 80W, either aloneorin combination with copper oxychloride, provided the best control of Corynespora leafspot of tomatoes in field plot trials with eight fungicides or combinations. Although not providing as effective a control, the use of Dithane 2–78 was the most cost effective based on yield per 100 m2or per kg of fruit in the first test. Disease intensity was significantly lower in plots sprayed with Bravo and Difolatan on a 3‐day schedule than on a 7‐day schedule through the first harvest in a second trial. Differences in disease intensity between treatments and the control were not significantly different at final harvest, which may indicate the importance of early season control. Yields from Bravo‐sprayed plots were significantly greater than yields from Difolatan‐sprayed plots, and yields from plots sprayed with either Bravo or Difolatan on 3‐ or 7‐day schedules were significantly greater than yields from unsprayed controls in this experiment. In a third experiment, disease Intensity was significantly lower in plots sprayed with Bravo or Difolatan, or with these fungicides applied in combination with copper oxychloride, than in the unsprayed control plots. The combinations with copper oxychloride were more effective than Bravo or Difolatan alone.

ISSN:0143-6147    

DOI:10.1080/09670878609371023

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The most important fungi consistently isolated from tomato plants naturally infected by the basal stem rot disease in Northern Nigeria were:Fusarium oxysporum, F. equlseti, F. solani, F. fusaioides, F. acuminatum, Trichoderma viride, T. harzianum, T. hamatum, Aspergillus flavus, A. niger, A. sydowiiandA. foetidus.Laboratory screening tests on potato dextrose agar (PDA) showed that only two out of 16 fungi, namelyT. virideandT. harzianuminvaded the colonies ofCorticium rolfsiiand completely Inactivated the pathogen in culture. The colonies of the majority of the test organisms (75%) were overrun byC. rolfsiimycelium. Greenhouse studies showed thatT. viridecompletely inhibited the incidence of the basal stem rot disease of tomato when inoculated on the same day as, or three days before, inoculation withC. rolfsii, T. virideandA. flavusinoculated three days after the pathogen, did not significantly reduce disease incidence on tomato. However, disease severity was slightly reduced (53.3–58.8%) whenA. flavuswas inoculated on the same day as, or three days before, inoculation withC. rolfsii.During both dry and wet season trials in the field, disease severity indices (2·6–4·3%), were very low in plots in whichC. rolfsiiwas co—inoculated withT. viride.Much higher disease indices (88·7–97·1%) were recorded in plots in which the pathogen was co‐inoculated withA. flavus

ISSN:0143-6147    

DOI:10.1080/09670878609371024

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Natural enemies ofLantana camaraL. found locally and the species introduced, established and distributed in India are reviewed. The occurrence of the natural enemies:Lantanop‐haga pusillidactyla, Ophiomyia lantanae, Teleonemia scrupulosa, Epinotia lantana, Hypenasp. (near,abyssinialis)andArchipssp.?micaceanain South India were determined in a survey. Distribution ofOctotoma scabripennisandUroplata girardifrom North to South India andE. lantanafrom South to North India is suggested. Introduction of other exotic natural enemies that have proven beneficial elsewhere, namelyCalcomyza lantanae, Neogalea esula, Plagiohammus spinipennls and Salbia haemorrhoidalisis recommended to suppress the weed.

ISSN:0143-6147    

DOI:10.1080/09670878609371025

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

House sparrow(Passer domesticus(Linn.)) damage to peach flower buds/flowers was observed during 1978–1985 in the Aggar Nagar (Ludhiana) residential locality. At the flower bud stage, sparrows destroy the buds completely by eating or damaging them so that no flowers are produced, but leaf buds and young leaves remain untouched. The average yield of the Flordasun peach cultivar is 75 kg per tree (Anonymous, 1985) but in the present case only 0 to approximately 2 kg fruit were produced per tree.

ISSN:0143-6147    

DOI:10.1080/09670878609371026

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor