Studies on the biology of black mould (Aspergillus niger) on temperate and tropical onions. 1. A comparison of sources of the disease in temperate and tropical field crops

Aspergillus niger colonies were present on 60–90% of the leaves sampled from onion crops grown under hot, tropical conditions (Shambat, Sudan), but only on 21% of leaves in crops grown under temperate conditions (Wellesbourne, UK). The seed stocks used in the Sudan were naturally contaminated with A. niger , whereas the fungus was absent from seed used in the UK. Inoculation of seed with A. niger resulted in an increase in the incidence of the fungus on onion plants (mean 83% of plants with affected leaves) in the field and on bulbs in store in crops grown in the UK. In the UK, A. niger is infrequent in the soil and air, but it is a major component of the soil and air mycoflora in the Sudan. Most of the bulbs grown in Sudan were contaminated with A. niger at harvest because of the high incidence of the fungus in the field.     

The role of seed-borne Aspergillus niger in transmission of black mould of onion

The incidence of Aspergillus niger (black mould) was found to be high on seed produced in hot (desert) climates. The fungus was transmitted from contaminated seeds to the cotyledons and first true leaves of seedling onions grown under controlled conditions. Seedlings grown from contaminated seeds had longer roots but shorter shoots than those grown from healthy seeds. Seed treatment with either benomyl plusthiramat the rate of 2.5 + 2.5 g active ingredient/kg seed or in hot water (15 min immersion at 60°C) eliminated the fungus in a naturally infected seed stock, untreated seed of which gave 30% infected seedlings.     

Aspergillus niger,the causal agent of black mould disease in date fruits,infects and colonizes flowers and young fruitlets

Black mould, caused by Aspergillus niger, is the main fungal disease affecting date fruits. Symptoms develop inside the fruit, at the inner space between the pulp and the seed. This study focuses on the aetiology of black mould disease in Medjoul fruit. We followed symptom appearance naturally and after artificial A. niger inoculation at different development and maturity stages. Symptoms developed in only a short period during early fruit ripening. However, fruits were commonly colonized at earlier stages of development. Artificial inoculation of flowers and setting fruitlets increased the level of fruit colonization, while fungicide spraying at these stages decreased colonization. Several weeks following flower inoculation by A. niger, mycelium could be detected on degenerating stigmas and carpels as well as between the fruit and the calyx. Following inoculation with an A. niger strain expressing green fluorescent protein (A. niger^GFP), the pathogen was detected on stigmas of setting fruitlets but not within the stigmatic tissue or the transmitting tract of the carpel. The A. niger^GFP strain was detected during fruit development below the base of the large fruitlets and above the calyx surrounding the vascular bundle leading into the fruit. The results suggest that A. niger can infect and colonize flowers and setting fruitlets, grows on the degenerating carpels, and remains latent at a protected site at the base of the fruit until ripening. It then induces the typical black mould symptoms. The significance of these results for developing means to cope with the disease is discussed.     

Studies on Botrytis spp. occurring on onions (Allium cepa) and leeks (Allium porrum)

Botrytis byssoidea (mycelial neck rot) was more prevalent than B. allii (sclerotial neck rot) on the leaves of field onions and the bulbs of stored onions grown in some of the areas where onions or onions and leeks had previously been grown sequentially.
B. byssoidea and B. porri were also isolated from leeks. Spores of B. allii, B. byssoidea (from onions and leeks), B. porri , and B. squamosa caused infection of seedlings of salad (green) and bulb onions.
Inoculation with B. squamosa spores caused severe infection of seedling leaves, but inoculation with mycelial discs caused little damage to onion bulb tissue. By comparison, mycelial discs of the remaining species were highly pathogenic to bulbs.
The practical implications of disease transfer of certain of these species between onions and leeks are discussed.     

榆近脉三节叶蜂生物学与防治技术研究

榆近脉三节叶蜂(Aprocers leucopoda Takeuchi)是近几年发现的一种新害虫,中国新记录种。该虫严重危害榆树,分布于甘肃天水海拔1 720~1 950 m之间,1年发生4代,以预蛹越冬。非越冬茧结于叶背;越冬茧结于2~5 cm表土中。幼虫食叶危害,每年5月上旬至8月下旬为猖獗危害期。以25%灭幼Ⅲ号胶悬剂和40%氧乐果乳油1 500倍液防治3龄前幼虫,防效达95%以上。     

花生新黑地珠蚧发生危害与防治

花生新黑地珠蚧是近年来在沙区严重危害花生的害虫之一。经观察 ,该虫在豫东 1年发生 1代 ,以 2龄幼虫(球体 )在土壤 10～20cm的土层中越冬 ,5月中下旬越冬球形体脱壳羽化为成虫 ,交尾产卵。 6月下旬为 1龄幼虫孵化盛期 ,孵化后的 1龄幼虫钻入土内 ,吸取花生根部汁液 ,是防治的关键时机 ,7月上中旬为 2龄幼虫危害盛期。     

The use of antioxidants (free radical scavengers) to control grey mould (Botrytis cinerea) and white mould (Sclerotinia sclerotiomm) in various crops

Eighteen free radical scavengers (antioxidants) were tested for their ability to control grey mould. Most of the compounds reduced disease significantly in at least one of the test hosts–leaves of tomato, pepper, Senecio sp., bean, eggplant, or rose flowers; however, the effective concentration varied between 0.1 and 100 m m . Selected antioxidants were tested further. Butylated hydroxy toluene (BHT), tannic acid, ascorbic acid and dimethyl sulfoxide (DMSO) at a concentration of 1 .0 m m controlled grey mould of tomato fruits. All these compounds except BHT controlled the disease on cucumber fruits. Antioxidants affected Rhizopus stolonifer on grape berries but not Botrytis cinerea or Aspergillus spp. Some combinations of antioxidants were found to be more effective than either compound alone when tested on pepper or tomato. The synergists ascorbic acid and citric acid improved the control activity of BHT, propyl gallate, benzoic acid and tert -butylhydroquinone on tomato leaves. Ethylene production was inhibited in tomato leaves treated with propyl gallate, ascorbic acid and benzoic acid, but not in pepper leaves. Ethephon or H₂O₂ increased the severity of grey mould on leaves of Senecio sp. Their effect was controlled by BHT and benzoic acid or by BHT, respectively. Four to six compounds reduced linear growth of B. cinerea isolates in culture at a concentration of 1.0 m m , and six more compounds were effective at 10.0 m m . However just five compounds inhibited conidial germination at the high concentration alone. Gluconic acid lactone, thiourea and propyl gallate reduced Sclerotinia sclerotiomm on lettuce by 51-76%. The multiple activity of antioxidants on the host plant interaction is discussed.     

The effects of direct harvesting and drying systems on the incidence and control of neck rot (Botrytis allii) in onions

Direct harvesting, with mechanical removal of the foliage (topping), of onion crops followed by post-harvest drying at ambient temperatures ( c . 18°C) resulted in an increase in the incidence of onion neck rot ( Botrytis allii ).
The disease was substantially reduced if topped onions were dried at 30°C with an airflow of 425 m³ air/h/tonne. The treatment was most effective if the crop was removed from the field for drying within 48 h of topping thus avoiding severe infection of the damaged green tissues of the necks of onions.     

不同杀菌剂防治香蕉黑星病药效试验初报

用5％霉能灵可湿性粉剂600倍，30％爱苗乳油2000倍液，75％百菌清可湿性粉剂800倍防治香蕉黑星病，防效达80％以上，值得在生产上使用。     

Heat treatment for the control of rose and carnation grey mould (Botrytis cinerea)

Thermal dip treatment for flower heads was found effective against grey mould of roses. Dipping of flowers in tap-water at 50 C for 20 40 s was more effective than at higher or lower temperatures and than for longer treatments. The treatment was effective in five out of six rose cultivars and in one carnation cultivar. A 60, reduction in disease severity following the treatment was observed in flowers naturally infected by Botrytis cinerea, whereas the treatment was not effective against artificial infection of flowers. Conditioning of flowers for 2 days at 10 C and high relative humidity before incubation under grey-mould-conducive conditions (15 C. high humidity) increased the efficacy of the thermal treatment. Moreover, the combination of heat with 3 mM catechol was additively more efficient in reducing grey mould. The surfactant Tween 20 (001 %) improved the effect of treatment at 45 C for 20 s. A combination of heat with the fungicide chlorothalonil did not improve effectiveness, whereas when polyoxin B was combined with heat it was better than either treatment alone. The temperature of petals at the edge and centre of flower reached 37 and 27 C, respectively, at the end of a 20-s incubation period in 50 C water. Conidia treated at 34-40 C for 10-20 s incited 60% less severe disease than conidia treated at 25 C in water.     

龙眼木毒蛾生物学及控制技术研究

木毒蛾(Lymantria xylina Swinhoe)属毒蛾科.在我国发生普遍,各地均有分布,其食性较广.主要寄主有木麻黄、相思树、茶、柿、柑橘、番石榴、芒果、枇杷、龙眼、荔枝等林木和果树.以往该虫是福建沿海防护林木麻黄的重要害虫,2003年上半年.突然在福建省厦门市部分龙眼树上大量暴发,并严重为害.其幼虫食量大,主要取食龙眼叶片、果穗等.据调查.受害重的龙眼树每片叶上有幼虫2～3头.一般龙眼树每穗幼虫1～2头.受害轻的龙眼树叶片被吃得残缺不全,受害重的叶片和果实全部被吃光,只剩下枝条,整株龙眼树似火烧过,呈褐色.龙眼木毒蛾从2003年起在本市部分龙眼果园开始成灾.并有向外扩展蔓延趋势,受害面积年年增加.国内在龙眼上.对木毒蛾的生态、发生、消长及防治等的研究和较详细的报道很少.笔者于2005～2007年,在前2年的调查观察、发生监测、为害特点及防治技术研究的基础上.对其进行了生物学及控制技术研究.     

马铃薯黑痣病生防菌的筛选及防治效果

由立枯丝核菌(Rhizoctonia solani)引起的马铃薯黑痣病由于常年连作和马铃薯种植规模扩大,病害发生越来越严重[1,2].目前马铃薯黑痣病的防治主要依靠农药的施用[3,4],但化学药剂的频繁使用会导致抗药性的产生、同时带来农药残留和环境污染等问题[5].从棉花根际土壤分离得到的多粘类芽胞杆菌Sx3可产生杀镰...     

Influence of fungicidal control of cucumber and tomato grey mould (Botrytis cinerea) on fruit yield

The fungicides tebuconazole, tebuconazole + dichlofluanid, fenethanil, diethofencarb + carbendazim, and vinclozolin combined with chlorothalonil were tested for their ability to control grey mould (Botrytis cinerea Pers. ex Fr.) of cucumber and tomato grey mould in greenhouses under commercial conditions. In winter 1987/88 the number of diseased female fruits of cucumber (Cucumis sativus L.) was reduced by diethofencarb + carbendazim (2·5 mg dm^?3 each) by 93% and by tebuconazole (2·5 mg dm^?3)(phytotoxic when alone) or tebuconazole (1 mg dm^?3) + dichlofluanid (4 mg dm^?3) by 54–57%. Vinclozolin (5 mg dm^?3) + chlorothalonil (25 mg dm^?3) significantly reduced disease incidence on fruits by 40%. Infection foci on cucumber stems were significantly decreased by vinclozolin + chlorothalonil. A more pronounced decrease was obtained with diethofencarb + carbendazim, tebuconazole, or tebuconazole + dichlofluanid. During the season of winter 1988/89, tebuconazole + dichlofluanid (1·5 + 6 and 3 + 12 mg dm^?3) and RH7592 (1 mg dm^?3) significantly reduced diseased fruits by 30–71%. Grey mould of tomato (Lycopersicon esculentum Mill.) leaves was reduced by more than 90% and on fruits by 78–87% when tebuconazole + dichlofluanid (1·5 + 6 and 3 + 12 mg dm^?3) or diethofencarb + carbendazim (2·5 mg dm^?3 each) were applied. Yields of cucumber fruits of the common parthenocarpic cv. Kasem 292 were weighed. There was no correlation between disease level and yield in any experiment, plot or date except for two measurements. Compesation in fruit production by the plant may be regarded as the reason for no positive yield response to efficient control. The possibility of reducing fungicide application is discussed. Control of grey mould on tomato resulted in yield increase.     

河北省苹果果实黑点病的发病规律及药剂防控研究

近几年,河北省苹果产区苹果果实黑点病大面积发生.该病害在河北省的流行规律以及时空分布尚不清楚,给病害防控带来挑战.2018年对河北省不同市区的4个果园分别进行黑点病调查,并对其在苹果树上的空间分布以及发生时间进行动态监测,开展田间药剂防效试验.结果表明:苹果果实黑点病在7月中下旬开始出现明显症状,果树中层内膛病果率较高...     

Aspergillus niger and a Penicillium sp. are not directly involved in the degradation of chlorsulfuron

When Aspergillus niger or a Penicillium sp. were grown in potato dextrose broth supplemented with chlorsulfuron, the herbicide concentration decreased by 97–99% within 78–96 h and the pH of the medium fell from 7.2 to between 2.4 and 3.1. If, during growth, the pH was maintained at or near neutrality, no decrease in herbicide concentration occurred. When sterile medium containing the herbicide was titrated with acid to mimic acid formation during fungal growth, the herbicide concentration again declined. Precipitation was not responsible for the observed decrease. The data indicate that, in laboratory media, these fungi do not directly metabolise the herbicide as previously thought. Chlorsulfuron degradation in perfused soil cores was not enhanced by inoculation with A. niger. Our results show that A. niger and a Penicillium sp. do not degrade chlorsulfuron.