摘要:

SUMMARYStudies in 1963–65 of the phytotoxic effects, on leaves, flowers and yields of blackcurrants, of sprays containing sulphur, particularly lime sulphur, showed that there was considerable variation in degree of effect between years and between experiments in the same year. It was difficult to damage flowers except at low temperatures, but if fruit set was affected then yield was depressed. Leaf scorching has to be very severe before yields are depressed. There was no evidence from preliminary experiments that sprays of seaweed extract reduced sulphur shock if used up to 3 days before lime sulphur application.The growth rate of shoots was reduced by 1/4–4% lime sulphur for short periods, dependent on concentration, but total bud numbers, flower/ vegetative bud ratios and yield were unaffected.It was found that no adverse effects of lime sulphur were carried over into the following y

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1967.tb04421.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYA continuation of previous trials in which three sprayers were used to apply 8.4 g. of Perenox in a range of spray volumes from 0.2 to 1.7 l. per tree confirmed that the volume of spray did not affect greatly the deposit retained on the branch surface. Branches were able to retain up to about 250 mg. Cu/m.2and it is considered that a volume equivalent to 100 gal./acre would provide the greatest margin of safety to compensate for inaccuracies of application, while avoiding serious run‐off. Where coffee was well pruned, intensive copper spraying raised the annual yield by about 2 cwt. of clean coffee per acre. Copper spraying did not provide an adequate control of coffee berry disease and, under certain circumstances, increased incidenc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1967.tb04422.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYBacterial canker and die‐back of poplars in Britain is caused byAplano‐bacterium populiRidé.Pseudomonas syringae(van Hall), which has been suggested as the causal agent, plays at most only a minor role in canker lesions. It may cause a shoot blight in spring, a distinct pathological condition frequently associated with bacterial canker.Marked variation in infectivity of bacterial slime between seasons and at different dates of collection within one year appears to be the main cause for situations in which varieties, resistant in trials to inoculation with slime, have proved susceptible in the field.Leaf scars afford the main avenues for infection but their infectibility declines rapidly during October. The implications of the temporal separation of availability of natural inoculum and available infection sites are discu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1967.tb04423.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYThe defoliating needle blight of pines caused byDothistroma piniHulbary (perfect stateScirrhia piniFunk&Parker) is severely damaging to plantations ofPinus radiataD. Don.,P. ponderosaLaws, andP. nigraAm. Symptoms and studies onP. radiataare reported.Disease severity has a linear relationship to stunting in very young trees, and a sigmoidal relationship to losses of height and diameter increments in 3‐year‐old trees, the most rapid losses occurring at disease severities between 25 and 75% blighted foliage. Height, independently of age, reduces disease severity. Maximum infection occurs at 0–5 ft. above ground level, while above 18 ft. there is significantly less attack.Rainfall of less than 1/2 in. weekly has little effect on disease increase and a mean weekly temperature of 65° F. or greater seems to be necessary for large disease increases; but the general environmental relations are too complex to be explained entirely quantitatively from the presen

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1967.tb04424.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYComparative studies were made of the responses of resistant and of susceptible Gem tomato plants to infection byVerticillium albo‐atrum.When inoculated through roots, there were striking differences in their responses. In susceptible plants, the foliar symptoms and amount of mycelium in the stem increased rapidly for some time. Then the mycelium started to disappear from the stem; this was accompanied by a check to the normal progress of symptoms, and by the formation of tyloses. In resistant plants, a limited invasion of the root and lower stem was accompanied by rapid and extensive tylosis. The mycelium soon disappeared from the stem and the plant then recovered from the initially mild symptoms. There was an inverse relationship between the amount of mycelium and the extent of tylosis in infected plants. The growth of susceptible plants was markedly reduced by infection. Total leaf area was much less because the newly produced leaves did not expand normally. The root system in infected plants was smaller because there were many fewer tertiary roots. In resistant plants infection stimulated growth.Tomato cuttings inoculated with conidia reacted similarly to root‐inoculated plants. Hyphae grew well in the vascular system of susceptible cuttings whereas in resistant cuttings the pathogen started to grow but soon disappeared.Detached leaves of susceptible plants, inoculated through cut ends, wilted more than did leaves from resistant plants. It is suggested that resistance is mainly of the active type that develops after infect

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1967.tb04425.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY