摘要:

SUMMARYMushroom compost was treated with nematicides and infested withAphelenchoides composticolaat the time of filling into growing containers. Yields of mushrooms from infested untreated control composts were reduced to 40–60% of yields from uninfested control compost. Yields from infested compost treated with fenamiphos emulsifiable concentrate (e.c.) at 10 or 20 mg a.i./kg, thiabendazole wettable powder at 40 or 60 mg a.i./kg or oxamyl granules at 20 mg a.i./kg were as high as from uninfested controls. Compost treated with granules of AC 64,475 up to 20 mg a.i./kg or ethoprophos or thionazin up to 80 mg a.i./kg gave yields significantly lower than uninfested controls.Numbers of nematodes rose to about 106/20 g of compost in untreated compost and then fell, and a similar peak occurred in treatments in which yields were substantially reduced by nematode damage. Treatments which yielded as well as the uninfested controls held maximum nematode numbers down to about 10V20 g of compost but populations stayed at this level or tended to rise while numbers in untreated compost fell. Incorporation of fenamiphos in casing or its application to the surface of beds 3 wk after cropping began gave lower yields than the uninfested control but mushrooms were being produced late in the cropping cycle.Fenamiphos e.c. at 20 mg ai./kg incorporated in compost is considered a practical preventive measure for control of A. composticol

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00682.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYThe incorporation of organophosphorous insecticides into the casing layer of mushroom beds reduces the numbers of mushrooms, according to a logistic relationship with log10(dose). The cumulative numbers at any flush are affected in this way, and the response of individual flushes may, therefore, be represented by the difference between two logistic curves. This explains the observed increases in numbers in the second and third flushes following diazinon treatment and in the fourth following thionazin, pirimiphos‐methyl and pirimiphos‐ethyl. No compensation in numbers followed chlorfenvinphos treatment. This decreasing response pattern reflected the increasing residual action of the insecticides.Mushroom size was inversely related to numbers but even when numbers in any flush were unaffected by the treatment, there was usually an increase in size. Thus yield increases occurred in most flushes at commercial concentrations of four insecticides (thionazin compensated only in the fourth flush) and total yields were increased by 8 to

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00683.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYA disease of mature tomato plants is described, the symptoms of which include brown discoloration and/or necrosis and collapse of the pith. These are sometimes accompanied by vascular browning, external dark brown to black stem lesions, bacterial flux from stem wounds and adventitious root formation. The disease, which appears to be favoured by high humidity and/or free water on the plant surfaces and by high N fertiliser, has been widespread on many glasshouse holdings in England since 1971 but has caused severe loss on only a few. It is thought to be caused by a new species of the genusPseudomonasfor which the nameP. corrugataRoberts and Scarlett is proposed.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00684.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYSevere diseases of pepper(Capsicum annuum), tomato(Lycopersicon esculentum), eggplant(Solanum melongena)and tomato eggplant(Solanum integrifolium)in West Africa were induced by pepper veinal mottle virus (PVMV). Five selected virus isolates were serologically similar and readily transmissible by aphids in the non‐persistent manner, but they differed in host range and/or symptoms induced in some susceptible species. One isolate from eggplant failed to infect pepper,Chenopodium quinoaand C.amaranticolor, and induced only local infections in tomato. An isolate from tomato failed to infect eggplant, and an isolate from tomato eggplant induced severe stunting inPhysalis floridana.The type strain, like the isolate from tomato, failed to infectNicotiana tabacumsystemically, but each caused severe systemic leaf and stem necrosis in tomato. None of the isolates infectedS. melongenacv. Long Purple, suggesting that PVMV might be controlled in this and perhaps other crop species by the use of immune or tolerant cultivars.All five isolates were serologically related to potato virus Y and some to six of 12 other potyviruse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00685.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYIn trials in 1973‐5 at the Glasshouse Investigational Unit for Scotland, the yield of fruit from tomato cv. Eurocross BB inoculated at the seedling stage with the Mil‐16 attenuated strain of tobacco mosaic virus was 5–8‐9‐4% greater than that from uninoculated plants which became naturally infected with a severe indigenous strain of the virus within 7–8 wk of planting. The increase in fruit yield, particularly of better grades, resulted in higher gross financial returns (up to 25p/plant) from inoculated plants. The yields from the Mil‐16 protected plants were up to 14% greater than those from plants artificially inoculated at the seedling stage with the indigenous severe virus.Inoculation with Mil‐16 had little adverse effect on early growth or the rate of fruit development on the first five trusses, but in 1973 the final yield of inoculated plants was depressed c. 5% compared with that from plants substantially free from infection for 14 wk after planting.In 1 year's test no benefit from inoculation with Mil‐16 was recorded in

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00686.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYTwo virus diseases, alomae and bobone, both of which are spread by the planthopperTarophagus proserpinaaffect taro(Colocasia esculenta)on Malaita, Solomon Islands. Where the diseases were endemic, plants of 284 of 297 cultivars died from alomae infection; the remaining 13 showed bobone symptoms on three to five leaves and then recovered, but symptoms later recurred on 12–13% of plants. Loss of yield due to alomae infection was directly proportional to the percentage of plants infected. Losses due to bobone ofc.25% could not be reliably detected unless insect pests were controlled. Frequent sprays with 0–1% malathion had no appreciable effect on the incidence of alomae, but fewer plants (30%) were infected when planted in November or December than when planted in May, June or August (64–94%).Because new taro crops are traditionally grown close to infected crops, insecticidal control of the vectors will probably be of limited use in decreasing spread of the dis

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00687.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYIn eastern Scotland seed‐borne infection with broad bean stain virus (BBSV) and/or Echtes Ackerbohnenmosaik‐Virus (EAMV) was detected in five of 39 seed lots of field bean in 1975 and in four of 21 commercial crops of field bean or broad bean sampled in 1975 or 1976. Tests failed to detect the main weevil vector of these viruses,Apion vorax, in 1975 and 1976 butSitonaweevils were found in most crops and were numerous in many, reaching maximum numbers in August. No spread of BBSV and EAMV was detected in commercial crops containing seed‐borne infection. In experimental field bean crops containing plants manually inoculated with virus, no virus spread was detected in 1975, and only 0–015% uninoculated plants became infected with EAMV in 1976.Sitona, therefore, was an inefficient vector.The percentage of virus infection in seed harvested from field bean plants manually inoculated 3, 5, 7 and 11 wk after emergence in the field was 1–5, 2–7, 0–4 and 0–06 for BBSV and 0–5, 2‐1, 0–6 and 0 for EAMV respectively. Seed harvested from unrogued and rogued plots of field bean grown from seed containing 3–4% seed‐borne infection produced 0–05% and no infected plants, respectively. Yield losses in field bean plants manually inoculated with virus before flowering were up to 20% but were much greater in plants infected through the seed. Loss in yield was largely caused by a decrease in number of seeds per pod.The absence ofA. vorax, the late arrival ofSitonaweevils in the crop and their inefficiency as vectors, and the smaller effects of BBSV and EAMV on crop yield than in southern England appear to make eastern Scotland very suitable for the production of bean s

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00688.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYThe yield of plants of monogerm cultivars of sugar beet artificially infected with both beet yellows and beet mild yellowing viruses was, on average, depressed 2–7% for every 100 ‘infected plant weeks’, equivalent to c. £25/ha at 1976 prices. The cv. Vytomo, previously recommended to growers as being tolerant of infection by virus yellows, had a high sugar content and abundant foliage but in field trials its actual yield of sugar was no greater when infected, and lower when virus‐free, than that of some other monogerm c

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00689.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYCell walls of tips and bases of laminae of flag leaves from 11 cultivars of winter wheat of varying susceptibility toPuccinia striiforntisyellow rust) were compared by examining their phenolic components released by treatment with a commercial cellulase. Isolated cell walls of both susceptible and resistant cultivars released water‐soluble carbohydrate esters of phenolic acids, the major acid detected beingtrans‐ferulic. There was no relationship between the amount of phenolic esters released by cellulase and susceptibility to yellow rust.The leaf lamina tips, which were much more susceptible to yellow rust than the corresponding bases, had lower cell wall contents than the bases and their walls were more degradable by cellulase. Examination of transverse sections of leaf laminae of cv. Little Joss showed that cells whose walls contained phenolic groups that gave a red colour reaction with p‐nitrobenzene diazonium tetrafluoroborate, occupied a larger area of leaf lamina bases than of the tips. A greater percentage of the abaxial epidermal cells of the bases, compared with the tips, had walls that gave this red colour reaction. We suggest that the presence of phenolic groups in these walls may be related to the greater resistance of the bases toP. striifo

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00690.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYEleven carrot cultivars were tested to compare their susceptibility to carrot fly attack at Wellesbourne and at Mepal, Cambridgeshire in 1969. Significant differences in the percentages of unattacked roots were observed but not all the cultivars behaved consistently in this respect at the two sites. Foliage height and the percentage unattacked roots were not significantly correlated for these cultivars.Four of the cultivars representing the different levels of susceptibility were retested in fen and in mineral soil in microplots at Wellesbourne in 1970. Soil type significantly affected plant growth but not the relative susceptibilities of the cultivars to carrot fly attack. Plant size was positively correlated with insect attack and accounted for most, but not all, of the differences in susceptibility between the cultivars. In 1971 also, cv. Royal Chantenay was significantly less attacked than Speed's Norfolk Giant from August to December even after allowing for the large differences between the two cultivars in plant size.The experiments demonstrated a consistent difference in the relative susceptibilities of cvs Royal Chantenay and Speed's Norfolk Giant. The difference was correlated with plant size but allowances for foliage and root size failed to account for all of the difference. The results suggested a more fundamental basis for part of the difference in the susceptibility of the cultivars to carrot fly attack.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00691.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY