Strawberry Gray Mold Research Articles

Investigation of Botrytis Cinerea Risk Forecasting Model of Strawberry in Lithuania

Grey mould, caused by Botrytis cinerea Pers.:Fr. is one of the most important strawberry diseases in Lithuania, like in other countries, where strawberries are grown. The efficiency of different disease management systems were analyzed at the Institute of Horticulture in 2010-2011. The B. cinerea risk probability at various regions of Lithuania was analyzed according to iMETOS ®sm grey mould risk forecasting model. Strawberry grey mould risk forecasting model indicates the risk of infection periods on the basis of the interaction between air temperature and leaf wetness duration. The model calculates how favourable is the period for the risk of infection. In periods where the risk is consistent (more than three days), higher than 60 points, a spray against grey mould should be applied. iMETOS®sm grey mould risk forecasting model gives the opportunity to optimize the usage of fungicides and reduce the number of applications and allows more efficient, ecologically and economically accepted control of strawberries grey mould.

In vitro and in vivo antifungal activates of the essential oils of various plants against strawberry grey mould disease agent Botrytis cinerea

In order to investigate the effects of antifungal essential oils on postharvest decay and some quality factors of strawberry fruit, experiments were conducted under in vitro and in vivo conditions. The antifungal activates of essential oils obtained from fennel, anis, peppermint and cinnamon at concentrations 0, 200, 400, 600 and 800 μL L−1 were investigated against Botrytis cinerea with four replications. In vitro results showed that the growth of B. cinerea was completely inhibited by fennel, cinnamon and anis essential oils at relatively low concentrations (400–800 μL L−1). In vivo results showed that all the used essential oils at all applied concentrations caused an increase in the shelf life and inhibited of B. cinerea growth on strawberry fruits completely in comparison to the controls. The results of this study confirmed the antifungal effect of four essential oils in both in vitro and on fruit postharvest.

Evaluation of Sporidiobolus pararoseus strain YCXT3 as biocontrol agent of Botrytis cinerea on post-harvest strawberry fruits

This study evaluated Sporidiobolus pararoseus (Sp) strain YCXT3 as biocontrol agent of Botrytis cinerea (Bc), the causal agent of strawberry gray mold disease. Efficacy of live yeast cells and volatile organic compounds (VOCs) of Sp in suppression of Bc on strawberry fruits was determined. Results showed that in dual cultures of Sp and Bc on potato dextrose agar at 20°C, Sp did not inhibit mycelial growth of Bc. However, inoculation of the yeast cell suspensions of Sp (1×105 or 1×106 yeast cells ml−1) on strawberry fruits resulted in reducing the disease incidence from 96–100% in the control treatment to 39–50% in the Sp treatment and the disease severity index from 5.1–7.0 in the control treatment to 1.1–1.9 in the Sp treatment. We found that the VOCs from the Sp cultures on yeast extract peptone dextrose agar were highly effective in inhibiting both the conidial germination and the mycelial growth of Bc. A total of 39 VOCs, including 2-ethyl-1-hexanol, were identified in cultures of Sp using GC–MS. Authentic 2-ethyl-1-hexanol was found to have strong anti-fungal activity against Bc with the IC50 values of 1.5 and 5.4μll−1 for conidial germination and mycelial growth, respectively. The VOCs from the Sp cultures were effective in suppression of gray mold disease under the air-tight conditions. This study suggests that the strain YCXT3 of Sp is a promising agent for control of Bc and production of VOCs is a valid biocontrol mechanism for this yeast strain.

Management of raspberry and strawberry grey mould in open field and under protection. A review

Grey mould, caused by Botrytis cinerea, is one of the most important diseases of strawberry and raspberry. In the UK, the majority of raspberry and strawberry production has recently switched to cropping under polythene tunnels. Although the risk of grey mould is greatly reduced under protection, a similar strategy is still adopted to manage grey mould on these crops. We first reviewed published studies on the epidemiology of grey mould on raspberry and strawberry, most of which are for crops grown in open field: (1) inoculum source comprises sclerotia on plant debris, plant organs and weeds, and resting mycelia on plant tissues. (2) Infection of flowers and the establishment of quiescent mycelium in floral parts is one of the main avenues for the rotting of ripe fruits. Thus, control of grey mould in open-field crops relies heavily on the scheduled application of fungicides during the flowering and early fruiting periods. (3) Recent research suggested possibility of B. cinerea as an endophyte. We carried out studies to understand the infection of flowers and fruit by B. cinerea on raspberry and strawberry crops grown under protection in order to assess whether management strategies developed for open crops are appropriate for crops grown under protections. Our main findings are: (1) covering crops early in the season did not significantly affect the incidence of raspberry fruit with latent infection by B. cinerea at harvest but reduced latent infection in strawberry. (2) Models developed for strawberry crops grown in the open did not give reliable predictions of flower infections on both strawberry and raspberry grown under protection. It was not possible to develop a predictive model for flower infection on raspberry grown under protection. (3) The level of ripe fruit with visual symptoms at harvest was low, usually close to zero. (4) Nearly all fruits from both sprayed and unsprayed crops were colonised by several fungi, including B. cinerea, within 7 days of harvest when stored at room temperatures. Based on these results, we question the value of scheduled fungicide applications to flowers and fruit for grey mould control under protection, and suggest that post-harvest fruit management, e.g. rapid cooling, is the key to prevent fruit from developing fungal rots before consumption.

Management of strawberry grey mould using mixtures of biocontrol agents with different mechanisms of action

Experiments were conducted using combinations of commercially available biological control agents (BCAs) to control infection of detached strawberry leaves by Botrytis cinerea Pers.;Fr. Combinations were tested either as mixtures, or as sequential treatments before and after disease loading. Five BCAs were initially tested, giving a range of mechanisms of antagonism. Only three (Sentinel™, Serenade™ and Trianum™) were effective in single agent experiments and were taken forward for combinatorial tests. Biocontrol efficacies, relative to the control, varied considerably among replicate trials, but all treatments involving Sentinel (BCA: Trichoderma atroviride P. Karsten LC52) and Trianum (BCA: Trichoderma harzianum Rifai T22) were very effective, either in sequential combination with other BCA or alone. Serenade (BCA: Bacillus subtilis (Ehrenberg) Cohn) was least effective, and sometimes did not result in any significant reduction in disease. Combinations of BCAs as mixtures resulted in less control (i.e., higher disease) than when the most effective BCA within the combination was applied alone, indicating possible antagonism between the BCAs. However, when two BCAs were applied sequentially about 48 h apart, there was no strong evidence for antagonism between the BCAs; this was also confirmed in an experiment using whole plants in controlled environment cabinets. We conclude that there was usually no benefit in applying two BCAs either together or sequentially, so in general we would not advise combinations as the method of choice. Thus, research is necessary to investigate possible interference among specific BCAs, since several BCAs may be applied simultaneously under field conditions to control several diseases.

Biocontrol Activity of Acremonium strictum BCP Against Botrytis Diseases

Biological control activity of Acremonium strictum BCP, a mycoparasite on Botrytis cinerea, was examined against six plant diseases such as rice blast, rice sheath blight, cucumber gray mold, tomato late blight, wheat leaf rust, and barley powdery mildew in growth chambers. The spore suspension of strain BCP showed strong control activities against five plant diseases except against wheat leaf rust. On the other hand, the culture filtrate of A. strictum BCP was effective in controlling only cucumber gray mold and barley powdery mildew. Further in vivo biocontrol activities of A. strictum BCP against tomato gray mold were investigated under greenhouse conditions. Control efficacy of the fungus on tomato gray mold increased in a concentration-dependent manner. Treatment of more than <TEX>$1{\times}10^6$</TEX> spores/ml significantly controlled the disease both in tomato seedlings and in adult plants. The high disease control activity was obtained from protective application of the strain BCP, whereas the curative application did not control the disease. Foliar infections of B. cinerea were controlled with <TEX>$1{\times}10^8$</TEX> spores/ml of A. strictum BCP applied up to 7 days before inoculation. In a commercial greenhouse, application of A. strictum BCP exhibited the similar control efficacy with fungicide procymidone (recommended rate, <TEX>$500{\mu}g/ml$</TEX>) against strawberry gray mold. These results indicate that A. strictum BCP could be developed as a biofungicide for Botrytis diseases under greenhouse conditions.

Biological control by Clonostachys rosea as a key component in the integrated management of strawberry gray mold

Gray mold, caused by Botrytis cinerea, is an important strawberry disease. As gray mold control is difficult, there is a need to evaluate integrated methods to successfully manage the disease. The efficiency of integrating Clonostachys rosea sprays, fungicide sprays, and crop debris removal to manage gray mold was evaluated in field experiments conducted in 2006 and 2007. Leaf colonization by C. rosea (LAC), average number of B. cinerea conidiophores (ANC), gray mold incidence in both flowers (Iflower) and fruits (Ifruit), and yield were evaluated weekly. In both years, LAC was higher in the treatments with no fungicide. When compared to the check, ANC, Iflower and Ifruit were most reduced in treatments that included C. rosea sprays. Maximal reductions were achieved with the combination of C. rosea sprays, fungicide sprays and debris removal (96.62%, 86.54% and 65.33% reductions of ANC, Iflower and Ifruit, respectively). Otherwise, maximal yield (103.14% increase as compared to the check) was achieved with the combination of the three treatments. With just C. rosea sprays, ANC, Iflower and Ifruit were reduced by 92.01%, 68.48% and 65.33%, respectively, whereas yield was increased by 75.15%. Considering the individual effects, application of C. rosea was the most efficient treatment. Chemical control was effective only in plots without debris removal. Elimination of crop debris was the least effective method in reducing gray mold incidence in both flowers and fruits. The integrated control approach enhanced the efficacy of the individual methods of gray mold control and provided high strawberry yield. An important component of this integrated approach it the biological control with C. rosea.

The mixture of kresoxim‐methyl and boscalid, an excellent alternative controlling grey mould caused by Botrytis cinerea

AbstractGrey mould, caused by the fungus Botrytis cinerea, is one of the most destructive diseases in greenhouses for which serious fungicide resistance has developed. Between 2003 and 2005, 213 isolates of B. cinerea from two geographical regions were characterised for baseline sensitivity to kresoxim‐methyl. In the absence of salicylhydroxamic acid (SHAM), the mean 50% effective concentration (EC50) values were 6.67 ± 0.61 (mean ± SD) and 0.37 ± 0.10 mg L−1 during growth and germination, respectively. In the presence of 100 mg L−1 SHAM, baseline sensitivities were distributed as unimodal curves with mean EC50 values of 2.38 ± 0.21 and 0.28 ± 0.09 mg L−1 for inhibiting growth and inhibiting germination, respectively. The mixture of kresoxim‐methyl and boscalid showed good control efficacy against strawberry grey mould disease. After the mixture was extensively used on strawberry for 2 years, 50 isolates were collected and determined for their sensitivity to kresoxim‐methyl and boscalid, respectively. The mean EC50 of germination inhibition by boscalid was 0.39 ± 0.08 mg L−1. The mean EC50 of germination inhibition by kresoxim‐methyl was 0.26 ± 0.07 mg L−1 in the presence of 100 mg L−1 SHAM. Sensitivities of B. cinerea to both kresoxim‐methyl and boscalid did not show any significant decrease. These results suggest that their mixture is a satisfactory alternative candidate for management of grey mould disease in greenhouses.

Biological control of strawberry gray mold by Clonostachys rosea under field conditions

Gray mold, caused by Botrytis cinerea, is an important strawberry disease in Brazil. As a component of a disease management program, we have been evaluating pathogen biological control with Clonostachys rosea, and selected four isolates as potential antagonists to B. cinerea. In 2006 and 2007, under field conditions, we compared the efficiency of the four C. rosea isolates (applied once or twice a week) with a weekly spray of procymidone alternated with captan in controlling gray mold. Following the applications and up to harvest, we evaluated weekly: leaf area colonization by C. rosea (LAC), average number of B. cinerea conidiophores on leaves (ANC), incidence of gray mold on both flowers (Iflower) and fruits (Ifruit), incidence of latent infections on fruits (Ilat), and yield. The applications of C. rosea twice a week provided higher LAC (16.97%), smaller ANC (10.28; 78.22 in the check treatment, sprayed with water), smaller IFlower (10.02%; 50.55% in the check treatment), and smaller IFruit (5.95%; 25.10% in the check treatment). Yield ranged between 3490 and 3750 g plot −1 with applications of C. rosea twice a week and between 1740 and 1910 g plot −1 in the check treatment. Ilat was 20% in the check treatment and less than 10% in the other treatments. Based on this 2-year study, at least two weekly applications of C. rosea are required for a successful gray mold management program.

In vitro inhibition of postharvest pathogens of fruit and control of gray mold of strawberry and green mold of citrus by aureobasidin A

Aureobasidin A (AbA), an antifungal cyclic depsipeptide antibiotic produced by Aureobasidium pullulans R106, has previously been shown to be effective against a wide range of fungi and protozoa. Here we report the inhibitory effects of AbA on spore germination, germ tuber elongation and hyphal growth of five pathogenic fungi including Penicillium digitatum, P. italicum, P. expansum, Botrytis cinerea and Monilinia fructicola, which are major pathogens causing postharvest diseases of a variety of fruits. AbA inhibited five pathogenic fungi by reducing conidial germination rates, delaying conidial germination initiation, restricting elongation of germ tuber and mycelium, as well as inducing abnormal alternations of morphology of germ tubes and hyphae of these fungi. The sensitivity of these fungi to AbA was pathogen species-dependent. P. digitatum was the most sensitive and M. fructicola the least. Importantly, AbA at 50 μg/ml was effective in controlling the citrus green mold and in reducing the strawberry gray mold incidence and severity, caused by P. digitatum and B. cinerea, respectively, after artificial inoculation. AbA and/or its analogs, therefore, hold promise as relatively safe and promising fungicide candidates to control postharvest decays of fruits, because AbA targets the inositol phosphorylceramide (IPC) synthase, an enzyme essential for fungi but absent from mammals.

Relationship Between Strawberry Gray Mold Incidence, Environmental Variables, and Fungicide Applications During Different Periods of the Fruiting Season

Incidence of gray mold (caused by Botrytis cinerea) on harvested strawberry fruit was evaluated with respect to environmental influences and fungicide regimes over four consecutive years. Disease incidence at harvest was correlated with the average daily values of 13 environmental variables during four discrete periods (or combinations thereof; these periods occurred from bloom until harvest and were defined by the timing of fungicide applications in designated treatments. Correlation coefficients in sprayed plots were determined with a variable weighting factor that most accurately accounted for fungicide influence on individual environmental variable X spray period combinations [...]

Tolerance of strawberry gray mold fungus, Botrytis cinerea, against thiophanatemethyl, polyoxin, and procymidone in Shizuoka Prefecture

Tolerance of strawberry gray mold fungus, <i>Botrytis cinerea</i>, against thiophanatemethyl, polyoxin, and procymidone in Shizuoka Prefecture