Berry infection and the development of bunch rot in grapes caused by Aspergillus carbonarius

The effects of different levels of inoculum of Aspergillus carbonarius and time of inoculation on berry infection and the development of aspergillus bunch rot on grapevines (cv. Sultana) were studied under field conditions. Inflorescences at full bloom were inoculated with aqueous spore suspensions of A. carbonarius containing 0 or 1 × 10⁶ spores mL⁻¹ in 2004/05 and 0, 1 × 10² or 1 × 10⁵ spores mL⁻¹ in 2005/06. In both years, the incidence of infection in inoculated berries was significantly higher than in uninoculated berries. Incidence of infection in berries from veraison until harvest was higher than at earlier stages of bunch development (berry set to berries that were still hard and green). Inoculation of bunches at veraison did not significantly increase A. carbonarius infection prior to harvest, at harvest, 6 days after harvest or when berries were over-ripe. Bunches inoculated at harvest did not significantly increase infection 6 days after harvest or when berries were over-ripe. Aspergillus carbonarius was isolated more frequently from the pedicel end (53·1%) than from the middle section (37·5%) and distal end (35·0%) of berries that were inoculated with 10⁵ spores mL⁻¹.     

Influence of the carpophagous generations of the European grapevine moth Lobesia botrana on grape bunch rots

The second and third generations of Lobesia botrana can cause both yield losses and spreading of grape bunch rots. The aim of this study was to know to what degree these generations of L. botrana influence the rots at harvest time. The study was carried out in two grape-growing areas of northeastern Italy where the moth completes two and three generations per year, respectively. In the context of 12 insecticide trials, samplings were conducted in different plots to estimate the number of larval nests of the second and third generations and that of rotten berries at harvest time. The data sets (number of larval nests and rotten berries) from the different trials were submitted to regression analyses. Gray mold was the most important grape rot. The second generation, in the area where L. botrana has only two generations per year, and the third generation, in the area where the moth completes three generations per year, can favor gray mold on and around berries bored by larvae. In contrast, groups of rotten berries non-contiguous to larval nests did not appear to be influenced by moth activity. In the area where the moth completes three generations per year the larval nests of the second generation did not show a significant influence on bunch rots at harvest time.     

Use of nitrate non‐utilizing (nit) mutants to determine phenological stages at which Botrytis cinerea infects wine grapes causing botrytis bunch rot

Botrytis bunch rot (BBR), caused by Botrytis cinerea, degrades wine grapes during ripening, even though infection can occur as early as flowering. Effective BBR management requires knowledge of whether some stages of fruit development are more important than others in relation to infection and BBR severity at harvest. Bunches of Vitis vinifera ‘Sauvignon blanc’ and/or ‘Pinot noir’ were inoculated in two vineyard trials and one glasshouse trial with nitrate non‐utilizing (nit) mutant strains at three phenological stages: early flowering, pre‐bunch closure (PBC) and veraison. Isolates recovered from symptomless berries at veraison and from bunches with symptoms at harvest were screened to measure the incidence of the nit strains used in the inoculations. It was found that latent infections, which resulted in BBR at harvest, could become established at all three phenological stages and no single stage was associated with greater latent incidence or harvest severity than any other stage. It was concluded that a proportion of BBR at harvest resulted from the expression of latent infections that had accumulated throughout the season. However, the time between infection and BBR symptom expression in near‐ripe grape berries was sufficiently short for polycyclic secondary infection to also contribute to epidemic development.     

Effect of the antagonist Candida sake on apple surface microflora during cold and ambient (shelf life) storage

This study examined the impact of the application of a biocontrol yeast, Candida sake CPA-1 (3 × 10⁶ colony forming units (cfu) ml^-1) on the resident microbial populations just prior to harvest, during 7 months cold storage and subsequent ambient shelf-life in two seasons on apples untreated or treated with a preharvest pesticide programme. The changes in populations of the antagonistic yeast ( C. sake) were also monitored. Generally, application of the antagonist had little effect on the total bacterial populations which remained very low both prior to harvest and subsequently during cold storage. White yeasts were predominant on the apples during the experimental period, with lower populations of pink yeasts. When apples were removed after 7 months to ambient conditions the yeast populations increased quickly but those apples treated with C. sake had significantly less white yeasts than untreated controls. The dominant filamentous fungi isolated were Cladosporium, Alternaria and Penicillium spp. Penicillium spp. which is responsible for major postharvest diseases was seldom isolated at preharvest but it became important during later cold storage and shelf life period. Populations of Cladosporium and Penicillium were significantly reduced by the C. sake treatment when removed from cold storage during the ambient shelf-life. In contrast, the Alternaria spp. were unaffected by the antagonist. The actual populations of C. sake applied decreased significantly immediately after application (24 h). However, they subsequently increased to a maximum after one month cold storage (10³ cfu g^-1), and populations increased again under ambient shelf-life conditions. The C. sake populations, and the resident microbial populations, were unaffected by preharvest fungicide applications. This study demonstrates that preharvest application of an antagonistic yeast such as C. sake has an impact on the resident mycoflora both during 7 months cold storage and during ambient shelf-life storage.     

猕猴桃采后病害鉴定和侵染规律研究

 猕猴桃果实在0℃贮藏4周后开始出现腐烂,贮藏19周,腐烂率高达50%以上。腐烂部位几乎都在果蒂和花端两点以外的果身上,极少数是蒂腐和花端腐烂。病原菌有7种,其中Botrytis cinerea,Penicillium sp.和Phomopsis sp.3种为优势菌。病原菌主要通过采收运输时造成的机械伤口侵染,未发现在果实过熟衰老前直接侵染。     

Occurrence of fungal pathogens of carrots on wooden boxes used for storage

Infested wooden boxes, previously used for carrot storage, were sampled in four commercial carrot production farms in Bradford Marsh, Ontario, and screened for fungal occurrence. At least 128 and 465 fungal isolates were recovered from these boxes in 2001 and 2002, respectively, and were classified into 10 taxonomic groups, including Alternaria spp., Aspergillus spp., Botrytis cinerea , Fusarium spp., Mucor spp., Penicillium spp., Rhizoctonia carotae , Rhizopus spp., Sclerotinia sclerotiorum and Trichoderma spp. A subsample of 27 putative pathogenic isolates was further tested for the ability to cause disease on carrots and to colonize wood surfaces under growth room and cold storage conditions. Approximately 60% of the taxa growing on wood caused lesions upon contact with intact carrots in cold storage. Isolates of S. sclerotiorum , B. cinerea and R. carotae caused the most severe diseases, developed most extensively on wooden surfaces in cold storage, and represented 12% of the recovered fungi. Isolates of Alternaria spp., Aspergillus spp., Fusarium spp., Mucor spp., Penicillium spp., Rhizopus spp. and Trichoderma spp. caused negligible or no disease on carrots and represented 88% of recovered fungi. Several of these fungi, however, showed potential to colonize wooden surfaces and cause disease on sliced carrots. This study suggests that pathogenic inocula occurring on used wooden boxes can initiate disease upon contact with healthy carrots and reusing infested boxes can affect carrots in storage.     

不同生态条件下葡萄叶部微生物区系分析

采用稀释平板法,对兰州市红古区露地和天祝县日光温室栽培‘红地球’葡萄叶部微生物进行分离计数和丝状真菌的纯化鉴定。结果表明,红古露地栽培葡萄叶部微生物的数量显著高于天祝日光温室。从幼果膨大期到果实成熟期,真菌数量均逐渐增加到最大值,其中红古葡萄叶部为2.89×102cfu/cm2,天祝葡萄叶部为0.49×102cfu/cm2,采收后均略有下降。细菌数量,红古葡萄叶部的变化与真菌相似,最高达12.68×102cfu/cm2,天祝葡萄叶部则在果实着色期达到最高值1.27×102cfu/cm2,后下降并趋于稳定。红古葡萄叶部的真菌种类和出现频率有一定的连续性,其中链格孢属(Alternaria)、盾壳霉属(Coniothyrium)、芽枝霉属(Cladosporium)在红古和天祝两种生态条件下均占优势,出现频率最高分别达到56.19%、44.3%和45.45%。青霉属(Penicillium)只在红古葡萄叶部分离到,根霉属(Rhizopus)和曲霉属(Aspergillus)只在天祝葡萄叶部分离到。筛选出21种对葡萄灰霉病菌菌丝有抑制效果的拮抗菌。     

Inhibition of Botrytis cinerea growth and suppression of botrytis bunch rot in grapes using chitosan

Chitosan inhibited growth of Botrytis cinerea in liquid culture and suppressed grey mould on detached grapevine leaves and bunch rot in commercial winegrapes. Germination of B. cinerea was completely inhibited in malt extract broth containing chitosan at concentrations greater than 0·125 g L^?1. However, treated conidia were able to infect detached Chardonnay leaves and pathogenicity was not affected, even after incubation for 24 h in chitosan at 10 g L^?1. When added after conidial germination, chitosan inhibited B. cinerea growth and induced morphological changes suggestive of possible curative activity. The effective concentration of chitosan that reduced mycelial growth by 50% (EC₅₀) was 0·06 g L^?1. As a foliar treatment, chitosan protected detached Chardonnay leaves against B. cinerea and reduced lesion diameter by up to 85% compared with untreated controls. Peroxidase and phenylalanine ammonia‐lyase activities were also induced in treated leaves. In vineyard studies, Chardonnay winegrapes exhibited 7·4% botrytis bunch rot severity at harvest in 2007 after treatment with an integrated programme that included chitosan sprays from bunch closure until 2 weeks preharvest, compared with 15·5% in untreated controls and 5·9% with fungicide treatment. In the following season, botrytis bunch rot severity was 44% in untreated Chardonnay at harvest and the integrated programme (21%) was less effective than fungicides (13·8%). However, in Sauvignon blanc winegrapes, the integrated and the fungicide programme each reduced botrytis bunch rot severity to 4% and were significantly different from the untreated control (11·5%). This study provides evidence that suppression of botrytis in winegrapes by chitosan involves direct and indirect modes of action.     

The Use of a Radioimmunosorbent Assay for Botrytis cinerea1

A radioimmunosorbent assay was developed for Botrytis cinerea which can be used to detect as little as 100 ng of Botrytis mycelium (dry weight). Of 22 fungi tested in the assay, all significant reaction was restricted to members of the Sclerotiniaceae. No reaction was obtained with representative isolates of Aspergillus, Alternaria or Peiticillium. Other Botrytis species gave the most reaction relative to B. cinerea. and related genera such as Monilinia and Sclerotinia yielded small reactions. The assay can be used to detect fi. cinerea infection of grape berries when as little as 0.1 % of homogenate from infected fruit is mixed with homogenate from sound fruit to simulate a minor infection. The assay of free run juice from various lots of grapes was highly correlated with visual assessments of infection in the field. Pursuant to various theories concerning bloom time infection, the assay was used to analyse the B. cinerea content of immature berry tips and floral debris; however, no evidence of such colonization was obtained.     

用于虫生真菌遗传转化的苯菌灵抗性菌株筛选

发展虫生真菌的抗药性是协调生防与化防,稳定真菌杀虫剂应用效果的一个重要策略。本研究从代表性地区采集植物病原样本,分离得到35株菌株,鉴定为3属5种,即灰葡萄孢霉Botrytis cinerea、扩展青霉Penicillium expansum、指状青霉Penicillium digitatum、长柄链格孢菌Alternaria longipes和茄链格孢菌Alternaria solani。应用菌落直径法测定其对苯菌灵的抗性,结果表明：供试的11株灰葡萄孢霉菌株中,最高EC50为936.2670μg·mL^-1;12株青霉属菌株中,最高EC50为0.0384μg·mL^-1;12株链格孢菌株中,最高EC50为703.5557μg·mL^-1。其中灰霉和链格孢属菌株中有4株EC50大于600μg·mL^-1的高抗菌株,即灰葡萄孢霉的菌株SD2和SD1以及茄链格孢的菌株CC2-2和LF1-2,这4株菌株可作为遗传转化抗性基因克隆的基础材料。     

Effect of aerated compost tea on grapevine powdery mildew, botrytis bunch rot and microbial abundance on leaves

Aerated compost tea (ACT), prepared from immature compost, was applied to foliage and fruit of grapevines (Vitis vinifera) to assess its potential for suppressing two important diseases: botrytis bunch rot, caused by Botrytis cinerea, and powdery mildew, caused by Erysiphe necator. An ACT applied to leaves of Cabernet Sauvignon vines in pots 7 days before inoculation with E. necator conidia reduced mean powdery mildew severity on the three youngest expanded leaves (at inoculation) to less than 1 %; mean severity on non-treated, inoculated leaves was 15 %. Multiple applications of ACTs at two vineyards in different growing seasons suppressed powdery mildew to <1 % mean severity on Chardonnay leaves (non-treated 79 % severity) and bunches (non-treated 77 % severity), and on Riesling leaves (non-treated 24 % severity). The same treatments reduced the incidence of Chardonnay bunches with latent B. cinerea and Riesling bunches with sporulating B. cinerea, although the level of botrytis bunch rot in both experiments was not economically damaging. The numbers of culturable bacteria, fungi and yeasts on Chardonnay leaves were higher than pre-treatment levels 10 days after ACT application, as were fungal numbers on Riesling leaves 21 days after treatment. Suppression by ACTs of two fruit and foliar pathogens of grapevine with different biology and epidemiology indicated potential for their use as a tactic in integrated disease management. Further testing of ACTs in a range of viticultural environments and application regimes will contribute to a better understanding of the impact of this tactic on disease, grape and wine quality.     

Reduced volume application of fungicides for the control of onion rots

A survey was conducted to define the fungi population contaminating onion bulbs in Israel during three growing seasons. Significant rots were found to be caused byBotrytis allii, B. cinerea andAspergillus niger. All the onion stocks tested showed infections, but the severity and identity of the pathogens varied between seasons.B. cinerea andB. allii were the most prevalent fungi in winter-harvested onions. Species ofAspergillus, Penicillium, Fusarium, Rhizopus andTrichoderma were also isolated. The first two were the only species found on summer onions. High fungal contamination had been the main factor affecting an attempt to improve the storage quality and shelf life of the harvested bulbs. Chemical disinfection using a reduced-volume application (RVA) technique was efficient in controlling the major storage rots (caused byA. niger andB. cinerea) of the bulbs, without the major disadvantages of the dipping method. The rate of control was directly correlated with the cover density of the deposited fungicide, but not with the amount deposited. The RVA technique should enable prolongation of postharvest shelf life and storability of onion bulbs.     

The Role of Saprotrophy and Virulence in the Population Dynamics of Botrytis cinerea in Vineyards

ABSTRACT Change in relative frequencies of the three main genetic types of Botrytis cinerea (Group I, Group II vacuma, and Group II transposa) were monitored over time from 1998 to 2000 in three Bordeaux vineyards not treated with fungicides. During 2000, Group I isolates, detected mostly at flowering comprised only 2.5% of the entire population. Within Group II, the complementary frequencies of vacuma and transposa isolates differed significantly depending on grapevine phenological stages and organs. Every year and at all sites, including one noble rot site, transposa isolates dominated at every stage, particularly on overwintering canes and at harvest (greater than 86.7% on berries). The complementary frequency of vacuma isolates reached a maximum on senescing floral caps (between 23.5 and 71.4%) and then decreased significantly until harvest on leaves and berries. In pathogenicity tests on grape berries, transposa isolates were significantly more virulent than were vacuma isolates. Mycelial growth rate was negatively correlated with virulence, notably on leaves in transposa and with double resistance to the fungicides carbendazim and vinclozolin. In vacuma, this double resistance was positively correlated with virulence on leaves. Change in the vacuma and transposa frequencies was most likely caused by differences in saprotrophic and pathogenic fitness. Possible interactions between fungicide resistance profiles and fitness are discussed.     

Biological Control of Botrytis cinerea in Cyclamen with Ulocladium atrum and Gliocladium roseum Under Commercial Growing Conditions

ABSTRACT The effect of treatments with conidial suspensions of Ulocladium atrum and Gliocladium roseum on leaf rot of cyclamen caused by Botrytis cinerea was investigated under commercial greenhouse conditions. Spraying U. atrum (1 x 10(6) conidia per ml) or G. roseum (2 x 10(6) conidia per ml and 1 x 10(7) conidia per ml) at intervals of 2 to 3 weeks during the production period and spraying U. atrum (1 x 10(6) conidia per ml) at intervals of 4 to 6 weeks resulted in a significant reduction of natural infections of petioles by B. cinerea. U. atrum or G. roseum (1 x 10(7)conidia per ml) was as effective as the standard fungicide program. B. cinerea colonized senesced leaves within the plant canopy and infected adjacent petioles and leaves later. The antagonists colonized senesced leaves and reduced B. cinerea development on these leaves. Thus, the inoculum potential on petioles adjacent to necrotic leaf tissues was reduced. The fate of U. atrum conidia on surfaces of green cyclamen leaves during a 70-day period after application was studied. The number of conidia per square centimeter of leaf surface remained relatively constant during the entire experiment. Sixty percent of the conidia sampled during the experiments retained the ability to germinate. When green leaves were removed from the plants to induce senescence and subsequently were incubated in a moist chamber, U. atrum colonized the dead leaves. Senesced leaves also were colonized by other naturally occurring fungi including B. cinerea. On leaves treated with U. atrum from all sampling dates, sporulation of B. cinerea was significantly less as compared with the untreated control. Our results indicate that early applications of U. atrum before canopy closure may be sufficient to achieve commercially satisfactory control of Botrytis leaf rot in cyclamen.     

Effects of three esca-associated fungi on Vitis vinifera L.: IV. Diffusion through the xylem of metabolites produced by two tracheiphilous fungi in the woody tissue of grapevine leads to esca-like symptoms on leaves and berries

Two naphthalenone pentaketides (scytalone and isosclerone) and α-glucans (pullulan) are produced in vitro and in planta by Phaeomoniella chlamydospora (Pch) and Togninia minima (Tmi), two tracheiphilous fungi associated with the ‘esca’ disease of grapevines. The possible role of such fungal metabolites in inducing symptoms on leaves and berries was studied in a vineyard of Vitis vinifera cv. Italia located in southern Italy. During early spring, pruning off two to four branches per vine allowed samples of xylem sap to be collected. Vine bleeding, assessed as ml day⁻¹ vine⁻¹, reached its maximum at bud burst and stopped within 28 days. The total amount of sap collected from healthy vines was about a quarter of that from esca-affected vines. During the same period, the leaf water potential of diseased vines increased progressively (i.e. showed less negative values), indicating a dysfunction in water and nutrient supply to the new growth. Both fungi were isolated from the xylem sap and from the woody tissue of branches and the trunk of diseased vines. Conidia isolated from the sap showed a high germination rate (>90%). Bioactive concentrations of the two pentaketides were detected in xylem sap, leaves and berries at various stages of seasonal growth. Exopolysaccharides, including pullulan, were found in the xylem sap. Absorption of culture filtrates of Pch and Tmi, as well as weak solutions of purified preparations of scytalone, isosclerone or pullulan, on detached leaves and berries caused symptoms similar to those shown by the esca-affected vines in the field.     

TOLERANCE OF CRANBERRY (VACCINIUM MACROCARPON AIT) TO SAN-9789: AN EXPERIMENTAL HERBICIDE

Summary. The experimental herbicide 4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazmone (SAN-9789) was applied to cranberry vines ( Vaccinium macrocarpon Ait. cv. Early Black) in April at rates of 0, 9, 13·5, 18, and 27 kg a.i./ha. No phytotoxicity on vine growth or appearance was detected in plots receiving 9 kg/ha but at 13·5 kg/ha a temporary chlorosis at the base of the cranberry leaf blade was observed. More extensive and permanent chlorosis was caused by the larger application rates of 18 and 27 kg/ha. No significant differences were detected between control and treated berries with respect to colour, percentage dry weight, and size. However, application rates of 27 kg/ha significantly reduced pectin content of fresh cranberries. Berries from vines treated in April with SAN-9789 did not contain detectable amounts of the herbicide at harvest time in September.
Résistance de la canneberge à gros fruits (Vaccinium macrocarpon Ait) à im herbicide expéri-mental, le SAN-9789     

Bacterial inflorescence rot of grapevine caused by Pseudomonas syringae pv. syringae

Molecular sequencing (rpoB) and standard pathological and microbiological methods identified Pseudomonas syringae pv. syringae (Pss) as the causal agent of bacterial inflorescence rot of grapevines (Vitis vinifera) in three vineyards in Tumbarumba, NSW, Australia in 2006 and 2007. Pss strains from shrivelled berries and necrotic inflorescences of diseased grapevines were used to inoculate leaves and inflorescences of potted cv. Semillon grapevines. Pss caused disease symptoms similar to those experienced in the field, including angular leaf lesions, longitudinal lesions in shoot tissues and rotting of inflorescences from before flowering until shortly after fruit set. High humidity promoted symptom severity. The necrotic bunch stem and leaf lesions were susceptible to the development of Botrytis cinerea infections. Cryo‐scanning electron microscopy (cryoSEM) indicated that Pss entered leaves and inflorescence tissues via distorted, open, raised stomata surrounded by folds of tissue that appeared as ‘star‐shaped’ callose‐rich complexes when viewed by UV light microscopy. In necrotic tissues, cryoSEM revealed Pss within petiole parenchyma cells and air‐filled rachis xylem vessels. This is the first report of inflorescence and hence fruit loss caused by Pss in grapevines. The disease is described as ‘bacterial inflorescence rot’ and regarded as one that expands the previously reported pathology of grapevines caused by P. syringae. This study also indicated that infection by Pss might promote destructive B. cinerea infections when the fungus is already present but latent, although further experimentation is needed to prove such an interaction.     

北京地区主栽西瓜品种种子携带真菌检测及鉴定

用离体平皿法对北京西瓜产区主栽的11个西瓜品种进行种子带菌检测、分离纯化和形态学、ITS序列比对,确定其属或种地位。结果表明:不同品种所带真菌种类有差异,种子表面携带的优势菌群主要为曲霉属Aspergillus spp.、青霉属Penicilliumspp.、链格孢属Alternariaspp.和镰刀菌属Fusariumspp.;种子内部寄藏真菌主要为青霉属、根霉属Rhizopus spp.和曲霉属。种子外部检出的主要病原菌有镰刀菌属的F.verticillioides,F.proliferatum及茎点霉Phomasp.;种子内部检出的病原菌有F.verticillioides和F.oxysporum。不同品种间种子表面携带真菌量与种子内部携带真菌率差异显著,但种子外部带菌量和内部种仁带菌率之间无显著相关性。本研究对开展西瓜种子处理研究有借鉴意义。     

Epidemiology of Toxin-Producing Fungi and Ochratoxin a Occurrence in Grape

Fungi responsible for ochratoxin A (OTA) production have been studied especially on cereals, where Penicillium verrucosum and Aspergillus ochraceus are to be considered the main producers. Until 1998, these fungi were also believed to be responsible for the production of the toxin in grape, but OTA-producing A. carbonarius and A. niger were identified in dried vine fruits in 1999. Further studies pointed out that mycoflora potentially responsible for the presence of OTA in grapes are present in the field. Aspergilli are dominant to Penicillia, and among these Aspergilli section Nigri. A. carbonarius probably plays an important role because of the high percentage of positive strains and the amount of OTA produced. Aspergilli section Nigri are present on grape bunches early in the season and their frequency increases during later growth stages. At early veraison and ripening, the incidence of colonised berries is more related to the year than to the growth stage, but not to visible symptoms, since it is normal to isolate fungi from intact berries. Differences in ochratoxin content of berries have been detected between years, when the same vineyards, managed in the same way, showed high levels (1999) or the absence (2000) of the toxin. The results suggest that meteorological differences between years and grape-growing areas are responsible for differences in OTA levels, but the data are at present insufficient to draw firm conclusions.     

Distribution of polygalacturonase, total phenolic substances, polyphenol oxidase and peroxidase in rot zones in sweet potato

Botryodiplodia theobromae causes a spreading rot of sweet potato, while Botrytis cinerea, Phoma exigua var. foveata and Fusarium solani var. coeruleum cause rots of limited extent. Cladosporium cucumerinum does not rot sweet potato tuber tissue. Whichever of these fungi is inoculated into tubers, a zone at the margin of the lesion can be clearly distinguished, from slightly affected but uninfected tissue on one side and infected rotted tissue on the other, by its high content of phenolic substances and polyphenol oxidase and peroxidase activities. Polygalacturonase is present in this zone for spreading B. theobromae lesions but not for the limited lesions caused by the other fungi. Total content of phenolic substances is generally greater in and around limited lesions.