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1.
Effects of fruit maturity, wound age, temperature and the duration of wetness periods on infection of apple fruits by conidia of the brown rot fungus, Monilinia fructigena , were studied. Inoculation of fruits on potted apple trees and harvested mature fruits showed that wounding was essential for infection by M. fructigena . On potted trees, there was a significant difference between the susceptibility of cvs Cox and Gala and this difference depended on wound age. The incidence of brown rot was affected greatly by fruit maturity and wound age. Wounds on younger fruits were more resistant to infection than those on older fruits, whilst the older the wound, the more resistant it was to infection. Furthermore, the degree of wound age-related resistance was greater on younger fruits than on older fruits. These relationships were well described by regression models. The effect of the duration of wetness periods was very small: increasing the duration of wetness periods reduced the incidence of brown rot on older wounds. For detached fruits, all those wounded were rotted after inoculation, except for those in two treatments under 20°C on fruits with wounds which were 8 days old. The incubation period of the fungus was generally very short. Wound age was the single most important factor influencing the length of the incubation period; the incubation period increased as wound age increased. 相似文献
2.
Pitch canker, caused by the fungus Fusarium circinatum , is a disease affecting many pine tree species. In California, Pinus radiata (Monterey pine) is the principal pine host affected by pitch canker. This investigation into factors affecting infection frequency by F. circinatum of P. radiata examined the influence of: (i) wound size; (ii) relative humidity; (iii) time of inoculation; (iv) inoculum density; and (v) wound age. Wounded branches sustained significantly more infections when large-diameter (1·6 mm) rather than small-diameter (0·5 mm) wounds were made. Infection frequencies tended to be higher at 100% RH than at ambient humidity, although these differences were not statistically significant. Infection frequencies were significantly higher on branches inoculated after 17·00 h than on branches inoculated before noon. Infection frequencies were significantly higher for wounded branches spray-inoculated with 5 × 107 rather than 1 × 107 spores mL−1 . Infection frequencies of pruning wounds declined as wounds aged. 相似文献
3.
Clive H. Bock James H. Graham Tim R. Gottwald Amanda Z. Cook Paul E. Parker 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(2):237-245
Citrus canker (Xanthomonas citri subsp. citri, Xcc) is one of the most serious diseases citrus in Florida, and elsewhere in the world. The disease causes yield loss and some fresh fruit trade restrictions may apply. Cultural management techniques such as windbreaks may work by not only reducing wind speed, but also reducing the period of exposure of susceptible foliage or fruit to those wind speeds that support infection from incoming inoculum. To investigate the effect of exposure period to inoculum of Xcc, seedlings of canker-susceptible Swingle citrumelo were exposed to sprayed inoculum for increasing periods at different wind speeds. The incidence and severity of citrus canker was assessed. In three experiments the incidence and severity of citrus canker most often increased with longer periods of exposure to inoculum, especially so at wind speeds of ≥16 m/s compared to wind speeds of ≤5 m/s (wind speed also increased disease incidence and severity). Regression analysis demonstrated relationships between period of exposure to inoculum and the percent infected leaves per plant, the number of lesions per plant, the number of lesions per infected leaf, and for the percent of infected leaves with lesions on the petioles at wind speeds of ≥16 m/s (R2?=?0.16–0.72). Due to the effect of inoculum exposure period and wind speed, attempts should be made to minimize exposure of canker-susceptible citrus when wind speed is highest and inoculum is available. Windbreaks should help minimize periods of exposure to splashed inoculum in high winds. 相似文献
4.
Potato tubers of five cultivais were incubated at five temperatures between 2 and 20°C for 1 month and then inoculated with Phoma exigua var. foveata and stored at 5°C. Larger rots usually developed on tubers previously incubated at the higher temperatures but cultivar differences were greatest where tubers had been incubated at 2°C. In another experiment, rot size was related to the duration of incubation at 20°C before inoculation.
In a series of experiments, tubers were stored at different temperatures after inoculation; other factors (e.g. wound type or r.h.) were also investigated in some of these. Combining the results of all experiments a linear decrease of % wounds infected (logit transformation) with storage temperature was demonstrated. The size of rots was not simply related to temperature, but tended to increase over the range 2–10°C and then stabilized or declined at higher temperatures. Relative humidity treatments of 75% v. 95% did not consistently affect either the incidence of rotting or rot size. The other factors investigated did not usually interact significantly with temperature.
The relevance of the results for resistance testing is discussed and a simple equation relating disease incidence to inoculum levels, type of damage and temperature is proposed. 相似文献
In a series of experiments, tubers were stored at different temperatures after inoculation; other factors (e.g. wound type or r.h.) were also investigated in some of these. Combining the results of all experiments a linear decrease of % wounds infected (logit transformation) with storage temperature was demonstrated. The size of rots was not simply related to temperature, but tended to increase over the range 2–10°C and then stabilized or declined at higher temperatures. Relative humidity treatments of 75% v. 95% did not consistently affect either the incidence of rotting or rot size. The other factors investigated did not usually interact significantly with temperature.
The relevance of the results for resistance testing is discussed and a simple equation relating disease incidence to inoculum levels, type of damage and temperature is proposed. 相似文献
5.
Factors affecting the severity of bacterial canker of pear caused by Pseudomonas syringae pv. syringae 总被引：1，自引：0，他引：1
Several factors affecting the severity of bacterial canker of pear were studied. In the orchard, infection of shoots by Pseudomonas syringae pv. syringae occurred only when the inoculum dose exceeded 106 colony-forming units/shoot. However, under favourable conditions in a growth chamber, cankers formed on detached shoots inoculated with 5 cfu/shoot. A second-order polynomial relationship was established between log10 transformed canker length and log10 transformed inoculum dose. In orchard and growth chamber experiments, shoots were susceptible from the time of bud swell until after fruit harvest. The severity of Pseudomonas canker of detached shoots increased if they were frozen at – 10°C for 24 h before inoculation. Shoots were most susceptible when inoculated immediately after wounding, and no cankers developed in the orchard when 3-day-old wounds were inoculated. Additionally, no cankers resulted from inoculation of leaf scars at leaf drop. Actively growing, current-season shoots were more susceptible than shoots that had set a terminal bud. The practical implications of these results are discussed as a basis for control of bacterial canker of pear. 相似文献
6.
Grapevine cultivars Cabernet Sauvignon (susceptible to Eutypa dieback), and Merlot (tolerant), were pruned three times during the dormant season (mid-December, mid-January and mid-February) and wounds on the 1-year-old canes were inoculated weekly with ascospores of Eutypa lata after pruning. No differences in susceptibility to infection were observed between cultivars, although in the vineyard they differed in symptom expression. Infection by E. lata varied with pruning date and the age of the pruning wound, and was higher and of longer duration with early pruning (December). At low temperature, infection of the pruning wounds by E. lata was increased, whereas the growth of other microorganisms was reduced. Moderate temperatures encouraged the growth of other microorganisms, notably Rhodotorula sp. This natural colonizer of grapevine pruning wounds was able to reduce the infection capacity of E. lata . It was more effective when inoculation with E. lata was carried out with low numbers of ascospores and when it was delayed until 14 days after application of the wound colonizer, infection being reduced by 95–100%. 相似文献
7.
Penyalver R García A Ferrer A Bertolini E Quesada JM Salcedo CI Piquer J Pérez-Panadés J Carbonell EA Del Río C Caballero JM López MM 《Phytopathology》2006,96(3):313-319
ABSTRACT Pseudomonas savastanoi pv. savastanoi causes olive knot disease, which is present in most countries where olive trees are grown. Although the use of cultivars with low susceptibility may be one of the most appropriate methods of disease control, little information is available from inoculation assays, and cultivar susceptibility assessments have been limited to few cultivars. We have evaluated the effects of pathogen virulence, plant age, the dose/response relationship, and the induction of secondary tumors in olive inoculation assays. Most P. savastanoi pv. savastanoi strains evaluated were highly virulent to olive plants, but interactions between cultivars and strains were found. The severity of the disease in a given cultivar was strongly dependent of the pathogen dose applied at the wound sites. Secondary tumors developed in noninoculated wounds following inoculation at another position on the stem, suggesting the migration of the pathogen within olive plants. Proportion and weight of primary knots and the presence of secondary knots were evaluated in 29 olive cultivars inoculated with two pathogen strains at two inoculum doses, allowing us to rate most of the cultivars as having either high, medium, or low susceptibility to olive knot disease. None of the cultivars were immune to the disease. 相似文献
8.
Components of resistance of apple to Podosphaera leucotricha were assessed in the glasshouse by spraying shoot tips of cultivars with conidia. Disease incidence (proportion of leaf surfaces with mildew) and colony numbers were higher and incubation periods correspondingly shorter on the older leaves. unrolled at the time of inoculation. Numbers of colonies were higher on the lower surface. Spore production per colony was higher on the younger leaves. In general, a short incubation period on a cultivar was associated with a high disease incidence, many colonies and high spore production. For some cultivars the association between these components permitted resistance to be classified as very high (cv. Discovery), very low (cv. Golden Delicious), or intermediate(cvs Bramley's Seedling. Suntan). The effects of inoculum concentration and post-inoculation environment (glasshouse or outdoors) on components of resistance were assessed in a further study. No interactions between cultivar and inoculum concentration were detected. There was generally an associated variation in components between cultivars within an environment, but inconsistencies in cultivar rankings were noted between the two environments and the two studies. Mean incubation period was shorter and colony area larger in the glasshouse than outdoors. There were significant differences in conidia/cm2 colony between cultivars only in the glasshouse. Components conferring high resistance in cv. Discovery and low resistance in cv. Golden Delicious were confirmed in both environments and in both studies. 相似文献
9.
Eutypa canker and dieback of apricot trees, caused by the ascomycetous fungus Eutypa armeniacae Hansf. et Carter, has been recorded in Europe, North America, Australia and South Africa. Samples of diseased sapwood yield the imperfect Cytosporina stage in culture, whereas perithecia of E. armeniacae, immersed in a stroma, develop 2 or more years after death of a branch in high-rainfall areas. The fungus is a wound parasite. Air-borne ascospores, disseminated during and after rain, infect xylem tissues which have been freshly exposed by pruning. Cankers develop around the infected wounds; leaves on that part of the branch distal to the canker subsequently wilt and die during summer. E. armeniacae has been detected on a diverse range of host species, hence elimination of inoculum is not feasible; both biological and chemical approaches to wound protection and ultimate disease control are under investigation. 相似文献
10.
2011年烟台苹果产区腐烂病发病情况调查与原因分析 总被引：6，自引：0，他引：6
为了解2011年烟台苹果产区腐烂病的发生情况,2011年5月,在腐烂病发病较重的栖霞、海阳等地选择21个农户的果园,对腐烂病的发生情况进行了调查.结果表明,21个果园中具有新病疤的病株率为68.20％,死株率为2.76％,平均受害枝量为23.98％,死枝量10.74％,病株率超过50％的果园占25％～30％,总体发病情况比一般年份严重.调查共发现967块新病疤,平均每株2.32块,其中源自剪锯口的病疤占80.04％,从旧病疤复发的病疤占60.29％.2010年秋季的连续阴雨、冬季低温和2011年春季干旱可能是导致烟台苹果产区2011年春季腐烂病大发生的主要原因.剪锯口是腐烂病菌侵染的主要途径,旧病疤复发是春季腐烂病发病的主体. 相似文献
11.
The infection efficiency and severity of leaf blotch on spring barley inoculated with three pathotypes of Rhynchosporium secalis from central Norway were studied under different temperature and humidity regimes. Seedlings of the cultivar Arve were subjected to two constant temperatures, 13° or 18°C. Dry periods of 8 h or longer before or after a wet period of 4 h, carried out in the first 48 h postinoculation, reduced disease severity assessed 16 days after inoculation. The effect of dry periods of up to 24 h was nullified when plants were subjected to high humidity for 48 h after the dry treatment. The disease developed most rapidly when the wet period was 48 h and the temperature 18°C. At or near the optimum temperature for R. secalis (18°C), leaf wetness duration as short as 2 h resulted in considerable disease. Isolates reacted differently to temperature. The most aggressive isolate caused severe disease irrespective of temperature (56–70% of the leaf area infected); however, disease severity caused by the least aggressive isolate was significantly higher at the optimum temperature compared with a lower temperature (13°C). This information can facilitate evaluation of weather data in relation to predicting leaf blotch for advisory purposes. 相似文献
12.
为了明确剪口龄期和水分胁迫对轮纹病菌从剪锯口侵染的影响,本研究采用脱脂棉蘸取轮纹病菌分生孢子悬浮液接种不同龄期和断水处理的‘富士’苹果枝条剪口,研究了剪口龄期和水分胁迫对轮纹病菌从剪口侵染的影响。结果表明,春季修剪形成的剪口在2个月内对轮纹病菌都较为敏感,接种发病率较高。夏秋季节形成的剪口在2周内对轮纹病菌非常敏感,2周后抗病性逐渐增强。苹果修剪前后,干旱能明显降低剪口对轮纹病菌的抗侵入和抗扩展能力。保护剪锯口不受侵染既能降低苹果苗木带菌率,又能有效控制轮纹病的危害。 相似文献
13.
The susceptibility of 1‐ and 2‐year‐old grapevine wood to botryosphaeria canker caused by Lasiodiplodia theobromae and Neofusicoccum parvum was evaluated in California in two seasons. In the 2007 dormant season, pruning‐wound susceptibility was highest when wounds were inoculated immediately after pruning in December (80% of pruning wounds were infected in Chardonnay for both fungal species and 75% and 98% in Cabernet Sauvignon for N. parvum and L. theobromae, respectively). In the 2008 dormant season, pruning‐wound susceptibility was highest in November in Chardonnay (86% and 93% for N. parvum and L. theobromae, respectively) and in December in Cabernet Sauvignon (71% and 75% for N. parvum and L. theobromae, respectively). The lowest infection rates (13–35%) were observed when vines were pruned and inoculated in March in both dormant seasons and for both cultivars. Susceptibility of pruning wounds did not differ significantly (P = 0·7612) between 1‐ and 2‐year‐old wood and consequently, pruning‐wound protection treatments should be applied to all wounds. In conclusion, grapevine pruning wounds were susceptible to infection by L. theobromae and N. parvum to varying extents throughout the dormant season in California (November–March), but, overall, susceptibility of pruning wounds was highest when inoculations were done immediately after pruning and decreased significantly as the interval between pruning and inoculation increased. Results of this study suggest that pruning grapevines in late winter (March) in California would significantly reduce the risk of infection by L. theobromae and N. parvum. 相似文献
14.
Experiments were conducted on olive plants in controlled environments to determine the effect of conidial concentration, leaf age, temperature, continuous and interrupted leaf wetness periods, and relative humidity (RH) during the drier periods that interrupted wet periods, on olive leaf spot (OLS) severity. As inoculum concentration increased from 1·0 × 102 to 2·5 × 105 conidia mL?1, the severity of OLS increased at all five temperatures (5, 10, 15, 20 and 25°C). A simple polynomial model satisfactorily described the relationship between the inoculum concentration at the upper asymptote (maximum number of lesions) and temperature. The results showed that for the three leaf age groups tested (2–4, 6–8 and 10–12 weeks old) OLS severity decreased significantly (P < 0·001) with increasing leaf age at the time of inoculation. Overall, temperature also affected (P < 0·001) OLS severity, with the lesion numbers increasing gradually from 5°C to a maximum at 15°C, and then declining to a minimum at 25°C. When nine leaf wetness periods (0, 6, 12, 18, 24, 36, 48, 72 and 96 h) were tested at the same temperatures, the numbers of lesions increased with increasing leaf wetness period at all temperatures tested. The minimum leaf wetness periods for infection at 5, 10, 15, 20 and 25°C were 18, 12, 12, 12 and 24 h, respectively. The wet periods during early infection processes were interrupted with drying periods (0, 3, 6, 12, 18 and 24 h) at two levels of RH (70 and 100%). The length of drying period had a significant (P < 0·001) effect on disease severity, the effect depending on the RH during the interruption. High RH (100%) resulted in greater disease severity than low RH (70%). A polynomial equation with linear and quadratic terms of temperature, wetness and leaf age was developed to describe the effects of temperature, wetness and leaf age on OLS infection, which could be incorporated as a forecasting component of an integrated system for the control of OLS. 相似文献
15.
Jan M. van Niekerk Frikkie J. Calitz Francois Halleen Paul H. Fourie 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(3):375-390
Trunk disease pathogens of grapevines, viz. Phaeomoniella chlamydospora, Eutypa lata and several species in Botryosphaeriaceae, Phaeoacremonium and Phomopsis are known to infect fresh pruning wounds by means of air-borne inoculum released after rainfall or prolonged periods of high
relative humidity. Recent surveys have demonstrated that most or all of these pathogens are present in climatically diverse
grape growing regions of South Africa. However, the factors controlling spore dispersal of these pathogens in vineyards were
largely unknown. To address this question, spore trapping was done in a Chenin Blanc vineyard in the Stellenbosch area, South
Africa, for 14 weeks during the grapevine pruning period from June to mid-September of 2004 and 2005. Hourly recordings of
weather data were done by a weather station in the row adjacent to the spore trap. Spores of E. lata and Phomopsis and species in Botryosphaeriaceae were trapped throughout the trapping periods of 2004 and 2005, with higher levels of trapped
spores recorded in 2005. The spores of all three pathogens were trapped during or after periods of rainfall and/or high relative
humidity. In neither of the 2 years were spores of Pa. chlamydospora or Phaeoacremonium spp. trapped. Results indicated that spore event incidence, as well as the amount of spores released during a spore event
of above-mentioned pathogens, were governed by rainfall, relative humidity, temperature and wind speed prior to and during
the spore events. 相似文献
16.
A. Dvenhuis 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(6):537-544
The effect of injury on disease incidence, incubation period and lesion development rate on caraway roots by Mycocentrospora acerina was studied in three laboratory experiments. After inoculation with M. acerina, disease incidence of injured roots was significantly (P< 0.001) higher than of non-injured roots. The incubation period of M. acerina was significantly (P < 0.001) shorter on injured roots than on non-injured roots. The incubation period shortened with increasing root injury level. Younger injured roots tended to be more resistant to M. acerina infection than older injured roots, expressed by longer incubation periods. The lesion development rate was, on average, higher on heavily injured roots than on non- or slightly injured roots. The lesion development rate remained fairly constant after the first emergence of the symptoms on the caraway root, until the whole root was colonized. Caraway roots carefully dug up in autumn frequently showed injuries enabling M. acerina to penetrate the roots. However, the correlation between root injury and root rot after cold storage was weak. Injury of roots had a stimulating effect on infection and development of M. acerina, but roots without wounds could be infected too. Some relevant field observations are discussed. 相似文献
17.
T. Beyers C. Vos R. Aerts K. Heyens L. Vogels B. Seels M. Höfte B. P. A. Cammue B. De Coninck 《Plant pathology》2014,63(1):165-173
In high‐tech, heated tomato glasshouses, stem infections caused by Botrytis cinerea usually end up girdling the stem, resulting in plant death and consequently high economic losses. Such infections originate primarily from wounds created during leaf pruning, a common cultural practice in which it is intended to remove leaves completely, resulting in smooth stem wounds. However, hasty leaf pruning often results in numerous petiole stubs accidentally left behind. In this study analysis of disease incidences clearly proved that pruning leaves flush to the stem resulted in absolute resistance of the stem wounds, whereas petiole stubs displayed a high level of susceptibility to B. cinerea. Postponing inoculation of wounds after pruning indicated that development of nearly complete resistance occurs within 48 h after deleafing. Monitoring of the wound wetness period showed that drying of the wound surface is not the cause of the decreased susceptibility, contrary to what was commonly believed. Tomato mutants deficient in disease signalling showed altered phenotypes for susceptibility to B. cinerea, indicating that defences against this pathogen in petiole stubs depend on ethylene signalling. Additionally, the decreased susceptibility of mutants deficient in the biosynthesis of jasmonates and abscisic acid suggest an antagonistic effect of these signal molecules. On the other hand, resistance of smooth stem wounds could not be altered by disruption of salicylic acid, ethylene, jasmonate or abscisic acid signalling. This indicates that this remarkable absolute resistance to B. cinerea does not depend on the major disease signalling pathways. 相似文献
18.
R. E. Stuckey J. C. Zadoks 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):175-185
In growth chamber experiments, seedlings of a susceptible wheat cultivar (Rubis) were inoculated with urediospores of wheat leaf rust. Inoculated seedlings were incubated in a moist chamber. The period of exposure to leaf wetness varied in duration and progressed with or without one or more interruptions of variable duration. During the interruptions the leaves with germlings were dry. At near-optimal temperature, leaf wetness periods of six h resulted in 60 to 65% of the pustules produced with 12 or 24 h wetness periods. Interruption of a 6 h leaf wetness period by a 1 h dry period was most damaging to the rust germlings at about three to four h after inoculation. The damage became visible as a reduction in the number of resulting pustules and as a prolongation of the median latency period. Epidemiological implications of leaf wetness interruptions are discussed. 相似文献
19.
ABSTRACT The effect of weather conditions on the infection of peach shoots by Taphrina deformans was investigated both under orchard conditions and in controlled-environment experiments. Leaf curl incidence and severity were related to rainfall, length of wet periods, and temperature during wetness and during the incubation period, as well as to the development stage of shoots. Surface wetness was more important than rainfall for infection to occur. Minimum rainfall for infection was 3 mm, with a wet period of at least 12.5 h; higher amounts of rainfall did not cause infection when the wet period they triggered was shorter. Wet periods initiated by dew or fog were too short for infection to occur. Infection occurred only when air temperature was <16 degrees C during the wet period and <19 degrees C during incubation. Logistic equations relating relative disease incidence and either duration of wetness or temperature were developed under controlled-environment conditions, with asymptotes at >/=48 h of wetness and 相似文献
20.
In vitro effects of temperature and wet periods on infection of oilseed rape by Alternaria brassicae
The influence of temperature and duration of wet periods on infection of oilseed rape by Alternaria brassicae was studied on detached leaves and pods, leaf disks and intact seedlings. Infections increased with age of leaf and the interaction between temperature and leaf age was highly significant. On older leaves infection was optimal at 25°C. There were many infections also at 15, 20 and 29 C but relatively few infections at 10°C. On pods most infections were observed at 20 C, the highest temperature studied. Infection at each temperature increased progressively with duration of surface wetness. The minimum wet periods for infection of leaves were 3 h at 20–25°C, 4 h at 15°C, 6–9 h at 10 C and 12–24 h at 5 C and for infection of pods, between 6 h and 9 h at 10°C and 6 h (or less) at 15°C and 20 C. On leaves, dry periods interrupting wet periods limited lesion development to that obtained with the initial wet period only; on pods some further infections developed when pods were re-wetted. Dry periods of 3 h and 6 h following the inoculation of pods reduced subsequent infection but there was no further reduction by longer periods of drying to 48 h. 相似文献