Effect of temperature of production of Botrytis allii conidia on their pathogenicity to harvested white onion bulbs

Botrytis allii colonies incubated at low temperatures have been reported to produce larger conidia that germinate faster and give rise to longer germ-tubes than those grown at room temperature. The present study compared the effect of conidia produced at 20°C and at 0 and –2°C on their pathogenicity to artificially inoculated white onion bulbs, and the effect of conidial concentration (5×10³ and 5×10⁴ conidia/mL) on disease incidence, lesion area, incubation and latent period during storage at 20, 5 and 0°C. At all storage temperatures and periods tested conidia produced at −2°C caused a higher disease incidence and larger areas of rot than those produced at higher temperatures. When the conidial production temperature was raised to 20°C, the duration of incubation on the bulbs inoculated with 5×10⁴ conidia/mL was more than doubled during storage at 0°C, tripled at 5°C, and took 50% longer at 20°C. The incubation period was not significantly affected by conidial concentration at 20°C, and only slightly at 5 and 0°C, but at low temperatures the latent period was longer because of the delay induced in sporulation. These data are consistent with the packers' opinion that cross-infection of spring onions by long-term refrigerated onions in grading lines caused earlier and heavier rotting.     

低温对葡萄孢菌(Botrytis cinerea)菌丝生长和孢子萌发以及对贮藏菊苣侵染力的影响

 本文主要研究葡萄孢菌(Botrytis cinerea)在20、10、4、2、0、-2和-4℃下菌丝生长和孢子萌发的情况,以及在同样温度下对菊苣(Cichorium intybus L.)致病力的影响。尽管在PDA培养基上0℃以下低温明显地抑制菌丝生长和推迟孢子的萌发时间,但葡萄孢菌仍能在-4℃下14d后达到100%的萌发率,24周后菌落的生长直径为10 mm。用Botrytis cinerea孢子接种的菊苣在-2℃下6周以前的发病率较低,在-4℃下8周以前没有病害发生,但随着贮藏时间的延长,发病率逐渐上升,12周后腐烂率达到77%和71%,病害严重程度指数分别为37和31。菊苣贮藏在-2℃和-4℃下后期腐烂率的快速增加可能与此时菊苣产生冷害有关。     

香蕉弯孢霉叶斑病菌生物学特性及对杀菌剂敏感性研究

香蕉弯孢霉叶斑病菌［Curvularia lunata (Wakker) Boed］适合生长的培养基有PSA、PDA和OMA;菌落生长、产孢和孢子萌发最适宜的温度为25～30 ℃,pH要求不严格为5～9;在碳源和氮源中,蔗糖、葡萄糖、尿素、磷酸氢二氨和硝酸钠有利于病菌生长和产孢;分生孢子萌发对湿度有严格的要求,RH≥80%以上分生孢子萌发,随湿度增加萌发率增高;光照对菌丝体无显著影响,光暗交替有利于孢子的形成; 孢子致死温度为55 ℃(10 min)。药物敏感性测定结果表明,6%戊唑醇微乳剂、25%丙环唑乳油、25%咪鲜胺水乳剂、25%戊唑醇乳油和25%苯醚甲环唑乳油对香蕉弯孢霉叶斑病菌菌丝生长均有较好的抑制效果,其中25%咪鲜胺水乳剂和25%苯醚甲环唑乳油的抑菌效果最好。     

The effect of temperature and water potential on the production of conidia by sclerotia of Botrytis squamosa

The rate of conidiogenic germination of Botrytis squamosa was highest at 16°C and the greatest numbers of conidia per sclerotium (up to 5 × 10⁴) were produced at temperatures of 5–10°C. At temperatures above 20°C, the percentage of sclerotia producing conidia declined rapidly. Decreasing water potential reduced the rate at which conidia were produced and also resulted in fewer conidia produced per sclerotium. However, conidia were produced at water potentials as low as −2 MPa, at which sclerotial germination was at least 60%. A simulation model that included effects of both temperature and water potential was developed from laboratory and field data obtained for conidial production in sclerotia exposed for periods of 1, 2, 3 or 4 weeks during an entire year. There was good agreement between conidiogenic germination predicted by the model and conidial production observed in onion plots artificially inoculated with sclerotia. Temperature and water potential were therefore considered to be the principal microclimatic factors affecting conidial production by B. squamosa. The role of sclerotia in the context of UK onion production is discussed.     

芒果疮痂病菌生物学特性研究

 本文主要研究了温度、pH、光照、维生素对芒果疮痂病菌(Sphaceloma mangiferae Bit.&Jenk.)孢子萌发、营养生长及孢子形成的影响,在14种半固体、固体培养基上对产孢量作了比较,还对湿度和营养对孢子萌发的影响做了试验。湿病原菌分生孢子萌发的温度范围为12℃~37℃,最适28℃;pH值范围为3~9,最佳pH 5;以自由水或饱和湿度条件下萌发率最高;连续黑光灯光照促进萌发;1%的葡萄糖液在28℃或33℃下明显增加了萌发率。该菌营养生长的温度范围为4℃~37℃,22℃~33℃生长良好,最适为28℃,与Bitancourt的报道基本相似;pH值范围为2~11,最佳为pH 5;黑光灯连续光照有利生长,VB₂、VB₆及V A对生长均有促进作用,在试验的培养基中PDA是生长最好的。该菌孢子形成的温度范围为12℃~33℃,最适温度为28℃;pH值范围为5~9,最佳为pH 7;光暗12 h交替处理比连续光照更利于产孢;VB₁及VA可促进产孢,但只有VA (50μg/L)既促进生长,又促进产孢;所试验的培养基中以PDA₊牛肉浸膏及PDA的产孢量最多,胡萝卜块是固体培养基中较理想的。     

Sporulation of Pyrenopeziza brassicae (light leaf spot) on oilseed rape (Brassica napus) leaves inoculated with ascospores or conidia at different temperatures and wetness durations

In controlled environment experiments, sporulation of Pyrenopeziza brassicae was observed on leaves of oilseed rape inoculated with ascospores or conidia at temperatures from 8 to 20°C at all leaf wetness durations from 6 to 72 h, except after 6 h leaf wetness duration at 8°C. The shortest times from inoculation to first observed sporulation ( l ₀), for both ascospore and conidial inoculum, were 11–12 days at 16°C after 48 h wetness duration. For both ascospore and conidial inoculum (48 h wetness duration), the number of conidia produced per cm² leaf area with sporulation was seven to eight times less at 20°C than at 8, 12 or 16°C. Values of Gompertz parameters c (maximum percentage leaf area with sporulation), r (maximum rate of increase in percentage leaf area with sporulation) and l ₃₇ (days from inoculation to 37% of maximum sporulation), estimated by fitting the equation to the observed data, were linearly related to values predicted by inserting temperature and wetness duration treatment values into existing equations. The observed data were fitted better by logistic equations than by Gompertz equations (which overestimated at low temperatures). For both ascospore and conidial inoculum, the latent period derived from the logistic equation (days from inoculation to 50% of maximum sporulation, l ₅₀) of P. brassicae was generally shortest at 16°C, and increased as temperature increased to 20°C or decreased to 8°C. Minimum numbers of spores needed to produce sporulation on leaves were ≈25 ascospores per leaf and ≈700 conidia per leaf, at 16°C after 48 h leaf wetness duration.     

苹果黑星病菌中国菌株生物学特性研究

 苹果黑星病菌(Venturia inaequalis(Cooke) Wint.)适合生长的培养基有苹果叶汁、苹果果汁、麦芽浸渍物、PSA、PDA、V8和马铃薯麦芽糖;适合产孢的培养基有苹果叶汁、V8和PSA。菌落生长和产孢适宜的pH值为5.0~6.5,温度为15~20℃。在碳源和氮源中,蔗糖、葡萄糖、果糖、麦芽糖、酵母提取物、硝酸钠和牛肉膏有利于病菌生长和产孢,硫酸铵抑制产孢,草酸铵抑制菌落的生长和产孢。20℃时,光周期为12 h,光照强度为600 lx条件下有利于病菌在PSA培养基上生长和产孢,其产孢量约为黑暗条件下的13倍。病菌分生孢子在水滴中萌发的适宜温度为20~25℃,最适pH值为5.0~6.5     

Stability and fitness of pyraclostrobin- and boscalid-resistant phenotypes in field isolates of Botrytis cinerea from apple

Phenotype stability, fitness, and competitive ability of pyraclostrobin- and boscalid-resistant isolates of Botrytis cinerea from apple were investigated. Stability of resistance was determined after consecutive transfers on potato dextrose agar (PDA) or being cycled on apple fruit. In vitro fitness components mycelial growth, osmotic sensitivity, conidial germination, and sporulation were evaluated on agar media. Pathogenicity, virulence and sporulation on apple fruit were evaluated at both 20 and 0°C. Competition between fungicide-resistant and -sensitive isolates on apple fruit also was evaluated. Resistance to the two fungicides was retained at levels similar to that of the initial generation after 20 and 10 transfers on PDA and five and three disease cycles on apple fruit at 20 and 0°C, respectively. Great variability in individual fitness components tested was observed among isolates within the same phenotype groups either sensitive or resistant to the fungicides but, when compared as phenotype groups, there were no significant differences in the mean values of these fitness components between resistant and sensitive phenotypes except that the phenotype resistant only to boscalid produced fewer conidia in vitro than sensitive isolates. Resistant isolates were as pathogenic and virulent on apple fruit as sensitive isolates. There was no significant correlation between the values of individual fitness components tested and the level of resistance to pyraclostrobin or boscalid, except that virulence at 20°C positively correlated with the level of resistance to the two fungicides. The final frequency of pyraclostrobin-resistant individuals in the populations was significantly decreased compared with the initial generation and no boscalid-resistant individuals were detected after four disease cycles on apple fruit inoculated with a pair mixture of a dual-sensitive isolate and one isolate each of the three phenotypes resistant to pyraclostrobin, boscalid, or both. The results suggest that resistance of B. cinerea to pyraclostrobin and boscalid was stable in the absence of the fungicides and that resistance to the two fungicides did not significantly impair individual fitness components tested. However, both pyraclostrobin- and boscalid-resistant isolates exhibited competitive disadvantage over the dual-sensitive isolate on apple fruit.     

布朗李叶枯病菌生物学特性研究

对布朗李叶枯病菌(Macrophoma kawatsukai Hara)生物学特性研究表明,该菌最适生长和产孢的培养基为布朗李果汁。菌丝生长和产孢的最佳碳源分别为蔗糖、麦芽糖和果糖;氮源分别为酪氨酸、谷氨酰胺、天门冬酰胺和半胱氨酸。菌丝生长最适温度25℃,最适pH5～7;分生孢子形成最适温度25～30℃,最适pH8,饱和湿度有利于产孢,阳光照射形成分生孢子器最多,紫外光照射对分生孢子器形成有一定的抑制作用。孢子萌发最适温度为20～30℃,最适pH6～9,相对湿度为90%～100%,以在水滴中萌发最好。布朗李杆煎汁和布朗李果汁对孢子萌发有促进作用。     

大蒜与黄瓜轮作控制黄瓜疫病及其化感作用初探

传统农业种植中常将目标作物与化感作物轮作控制土传病害,但对化感作物控病机制研究较少。本文研究了温室大蒜与黄瓜轮作对黄瓜疫病的控制效果,并进一步研究了大蒜组织挥发物和浸提液对甜瓜疫霉Phytophthora melonis及黄瓜种子萌发的影响,以期为利用大蒜与黄瓜轮作控制黄瓜疫病提供理论指导。结果表明,大蒜与黄瓜轮作可以有效降低黄瓜疫病的发生;大蒜不同组织挥发物和浸提液对P.melonis的各生长阶段都表现出显著的抑菌活性,其中蒜瓣的抑菌活性最强,挥发物(紫皮蒜/白皮蒜)在含量0.5 g/皿时对菌丝生长的抑制率均为100%;蒜瓣浸提液(紫皮蒜/白皮蒜)在浓度1.67 mg/mL时对菌丝生长的抑制率分别为32%和45%;在浓度0.25 mg/mL时对游动孢子萌发的抑制率分别为98%和53%。另外,大蒜挥发物和浸提液在低浓度或含量对黄瓜种子的萌发并无显著抑制效果,但在中高浓度或含量会表现出延缓生长的现象。综上所述,大蒜不同组织产生和释放的化合物对P.melonis具有抑制活性,在生产上可以利用大蒜或大蒜秸秆与黄瓜轮作控制黄瓜疫病的发生。     

18种化学农药与绿僵菌相容性研究

本文检测了18种常用低毒化学农药对生防真菌绿僵菌Metarhizium anisopliae孢子萌发、菌丝生长及产孢的影响,分析它们与绿僵菌的相容性。总体看,杀虫剂、植物生长调节剂和除草剂与绿僵菌的相容性好于杀菌剂。其中,氰戊菊酯与绿僵菌相容性最好,即使在10倍的推荐浓度下,对孢子萌发无影响,对菌丝生长速度和产孢量的抑制率只有25.13%和38.63%。高效氯氟氰菊酯和乐果与绿僵菌也有较好的相容性,在推荐的田间使用浓度下,孢子萌发抑制率为30%左右,对菌丝生长和产孢量基本没有抑制。溴氰菊酯、啶虫脒、吡虫啉、甲霜灵、氟乐灵、阿维菌素、敌百虫、毒死蜱和波尔多液与绿僵菌有一定的相容性。矮壮素、哒螨灵、多菌灵、甲基硫菌灵、代森锰锌和三唑酮与绿僵菌相容性很差。     

荔枝炭疽病菌生物学特性的研究

 本文主要研究了温度、湿度、pH值、光照、营养对荔枝炭疽病菌(Colletotrichum gloeosporioides Penz.)生长、产孢和孢子萌发的影响。该菌菌丝生长的温度范围为8~38℃,最适28℃;产生分生孢子的温度范围为12~36℃,最适28~32℃;分生孢子萌发的温度范围为8~38℃,最适28~32℃。在pH 3~10的范围内该菌均能生长和产孢,菌丝生长最适pH 5~6;产生分生孢子最适pH3~4,分生孢子萌发最适pH 6~7。分生孢子在饱和湿度或水滴中萌发快,相对湿度低于85%时不能萌发。光照处理对该菌生长发育无显著性影响。葡萄糖、蔗糖、麦芽糖、果糖对分生孢子萌发有促进作用。分生孢子的致死温度为50℃ 10 min,菌丝体的致死温度为60℃ 30 min。     

辣椒褐斑病菌生物学特性研究

本文对辣椒褐斑病病原菌Cercospora capsici Heald et Wolf的生物学特性进行了研究,结果表明,不同的营养、温度、pH等条件对菌丝生长和孢子萌发有显著影响。病菌菌丝的生长以PDA培养基为最适;适宜温度为20~25℃,最适温度为25℃;最适pH为8.0~9.0,光照对菌丝生长没有明显的促进作用,菌丝致死温度及时间为55℃ 10 min。分生孢子萌发适宜碳源为1%的蔗糖溶液,适宜氮源为1%的甘氨酸溶液;孢子萌发适宜温度为20~30℃,最适温度25℃;最适pH为5~6,光照对孢子萌发没有明显的促进作用,分生孢子致死温度及时间为52℃10 min。     

黄脉爵床棒孢霉叶斑病病原菌及其生物学特性鉴定

 明确黄脉爵床棒孢霉叶斑病病原菌及其生物学特性,为防控提供理论依据。通过病原菌分离、形态特征观察、致病性测定、rDNA-ITS序列分析、生物学特性及寄主范围测定等研究,证明该病病原菌为山扁豆生棒孢Corynespora cassiicola;菌丝生长及产孢适宜温度20℃~28℃,孢子萌发适宜温度24℃~32℃,菌丝致死温度49℃处理10 min;菌丝生长适宜pH 6~10,产孢适宜pH 4~8,孢子萌发最适pH 8;光暗交替适合菌丝生长与产孢,连续光照可抑制菌丝生长;菌丝生长量由少到多培养基顺序为CA、PCA、PDA、CMA、OA,而PDA上产孢最多;刺伤接种,病菌可侵染喜树(Camptotheca acuminata)等植物。黄脉爵床棒孢霉叶斑病病原为山扁豆生棒孢C. cassiicola,病菌易产孢,寄主广,潜育期短。该病菌侵染黄脉爵床为首次报道。     

Infection of ryegrass by three rust fungi (Puccinia coronata, P. graminis and P. loliina) and some effects of temperature on the establishment of the disease and sporulation

Experiments were conducted to examine the processes leading up to the infection of Lolium temulentum by crown rust ( Puccinia coronata ), stem rust ( P. graminis ) and brown rust ( P. loliina ), and the effects of temperature on these processes and sporulation. Uredia of all three rusts were produced freely if the adaxial leaf surface was inoculated, but did not form following inoculation of the abaxial surface. Light and scanning electron microscopy revealed abnormal growth of germlings on the abaxial surface which had amorphous sheet-like epicuticular waxes and very few stomata. On the adaxial leaf surface germ tubes of all the rusts orientated at right angles to the long axis of the leaf. However, the directional growth of germ tubes was often disrupted when they contacted the surface of bulliform cells at the base of leaf grooves. For P. loliina the optimum temperatures for urediospore germination and sub-stomatal vesicle formation were 12–16°C, and 8–20°C for appressorium formation. The optimum temperatures, for the same stages of fungal development, for P. coronata and P. graminis were higher. Urediospore production of P. loliina was higher at 10°C than at 25°C, but was similar at both temperatures for P. coronata .     

纳他霉素对灰葡萄孢不同生育阶段菌体的毒力及其生物学性状的影响

以多菌灵为对照药剂,采用生长速率法、悬滴法和浸渍法分别测定了不同温度下纳他霉素对灰葡萄孢Botrytis cinerea菌丝生长、分生孢子萌发和菌核萌发的毒力,研究了常温下两种药剂对菌株产孢和菌核形成的影响。结果表明:纳他霉素及多菌灵对灰葡萄孢不同生育阶段菌体的抑制作用随温度降低而有不同程度增强;分生孢子对药剂最为敏感;温度对药剂对菌丝毒力的影响最显著;多菌灵对菌株不同发育阶段的抑制活性均高于纳他霉素。供试药剂对菌株产孢时间和菌核产生时间无显著影响,但多菌灵可显著刺激菌株产孢和菌核形成。     

Effects of temperature and leaf age on conidial germination and disease development of powdery mildew on rubber tree

Powdery mildew is an important disease of rubber trees worldwide. To assess the effects of temperature and leaf age on conidial germination and disease development, conidia were inoculated onto rubber tree seedlings with leaves at three phenological stages (copper bronze, colour-changing, and light green) and then incubated at six constant temperatures (10, 15, 20, 25, 30, and 35°C). Leaf age did not affect conidial germination (p = .296) whilst temperature did (p < .0001), although conidia were able to germinate at all tested temperatures. The estimated optimal temperature for conidial germination was 23.2°C. Leaf age, temperature, and their interactions had significant effects on conidial infection and hypha number (p < .0001). At 10 and 35°C, more than 2 and 4 days were needed for infection to complete, respectively, compared to <2, 1, 0.5, and 0.5 days for 15, 20, 25, and 35°C, respectively. Sporulation and mildew symptoms were only observed on those inoculated leaves of all stages at 20 and 25°C, and at the copper bronze stage only at 15°C. The latent period on the copper bronze leaves at 15°C was longer (9 days) than at 20 and 25°C (4 days). The latent period at 20 and 25°C increased from 4 to 7 days as the leaf development stage increased from copper bronze to light green. Therefore, temperature affected germination and postgermination growth of rubber tree powdery mildew, whereas leaf age primarily affected postgermination growth of the pathogen.     

Latent infection of winter oilseed rape by Leptosphaeria maculans

Plants of oilseed rape, cultivars Primer and Jet Neuf, were grown in a glasshouse and inoculated at G.S. 2.4–2.7 with pycnidiospores or ascospores of Leptosphaeria maculans. The plants were kept for a further 2–4 weeks at 14°C and then transferred, together with uninoculated plants, to a polythene tunnel in winter. The majority of stems of inoculated plants did not have macroscopic symptoms of L. maculans infection 6 weeks after inoculation. Examination of whole mounts of peripheral tissue and transverse sections of fixed and embedded portions of these stems revealed intercellular septate fungal hyphae, often deep in non-necrotic cortical tissue, in symptomless inoculated plants but not in uninoculated plants. L. maculans was recovered following surface sterilization of adjacent portions of the same stems. When symptomless inoculated plants were transferred to a glasshouse at 18–20°C, cankers soon developed. The significance of these latent mycelial infections to canker development in the field is discussed.     

Prestorage heat treatment reduces pathogenicity of Penicillium expansum in apple fruit

Penicillium expansum is one of the main postharvest pathogens of apples in Israel. Heating apple fruit inoculated with P. expansum for 96 h at 38°C completely inhibited decay development. Fruit held for 24 h at 42°C or 12 h at 46°C had significantly reduced decay after an additional 14 days incubation at 20°C, compared with unheated inoculated control fruit. Mycelial growth and percentage spore germination in vitro were inversely proportional to length of time of exposure to various temperatures. The ET₅₀ for spore germination was 42, 34 and 20 h at 38, 42 and 46°C, respectively, while the ET₅₀ for mycelial growth was 48, 44 and 36 h at those temperatures. When Penicillium spores were incubated on crude extract prepared from the peel of apple fruits held 4 days at 38°C, germ tube elongation was significantly reduced, while the walls of the tubes were thicker, compared with germ tubes from spores incubated on crude extract prepared from peel of non-heated fruit. The evidence presented here supports the hypothesis that the effect of heating on the decay of apples caused by P. expansum is not only the result of direct inhibition of fungal germination and growth by high temperature, but is also partly due to the formation of an inhibitory substance in the heated peel.     

小麦根腐叶斑病菌生物学特性的研究

 本文报道了研究小麦根腐叶斑病菌(Bipolars sorokiniana)在不同条件下的孢子萌发.菌丝生长和孢子产生的结果.小麦根腐叶斑病菌的孢子可在pH2.2-12.4的磷酸缓冲液中萌发,萌发的温度范围为3-39℃,最适温度22℃.菌丝生长的温度范围4-37℃,生长的pH范围为2.7-10.3,最适PH因培养基和接种方法不同而异.产孢温度11-35℃,适温20-24℃.碱性培养基(pH9以上)和黑暗下产生的孢子细而短,延迟孢子成熟,光照则促进孢子的发育.