Strawberry Disease Research Articles

Real-Time Detection of Strawberry Powdery Mildew Disease Using a Mobile Machine Vision System

Strawberry cropping system relies heavily on proper disease management to maintain high crop yield. Powdery mildew, caused by Sphaerotheca macularis (Wall. Ex Fries) is one of the major leaf diseases in strawberry which can cause significant yield losses up to 70%. Field scouts manually walk beside strawberry fields and visually observe the plants to monitor for powdery mildew disease infection each week during summer months which is a laborious and time-consuming endeavor. The objective of this research was to increase the efficiency of field scouting by automatically detecting powdery mildew disease in strawberry fields by using a real-time machine vision system. A global positioning system, two cameras, a custom image processing program, and a ruggedized laptop computer were utilized for development of the disease detection system. The custom image processing program was developed using color co-occurrence matrix-based texture analysis along with artificial neural network technique to process and classify continuously acquired image data simultaneously. Three commercial strawberry field sites in central Nova Scotia were used to evaluate the performance of the developed system. A total of 36 strawberry rows (~1.06 ha) were tested within three fields and powdery mildew detected points were measured manually followed by automatic detection system. The manually detected points were compared with automatically detected points to ensure the accuracy of the developed system. Results of regression and scatter plots revealed that the system was able to detect disease having mean absolute error values of 4.00, 3.42, and 2.83 per row and root mean square error values of 4.12, 3.71, and 3.00 per row in field site-I, field site-II, and field site-III, respectively. The slight deviation in performance was likely caused by high wind speeds (>8 km h−1), leaf overlapping, leaf angle, and presence of spider mite disease during field testing.

Impact of Chitosan, Trichoderma harzianum, Thyme Oil and Jojoba Extract against Fusarium Wilt Disease of Strawberry

The impact of chitosan, Trichoderma harzianum, thyme oil and jojoba extract against F. oxysporum, wilt disease of strawberry, was studied in laboratory and throughout the following growing seasons of (2018 and 2019) in greenhouse. The antagonistic biocontrol agent, Trichoderma harzianum, was isolated and identified in lab at the Faculty of agriculture Saba Basha, Alexandria, Egypt. In laboratory tests, the effect of the tested biocontrol agents on fungal mean growth in vivo was determined. In the greenhouse experiments, the treatments were performed in three application methods: foliar, soil drench and the mixed foliar/soil method.In lab tests, Chitosan® (4g/l) followed by T. harzianum and Top perfect® (4ml/l) reduced the fungal growth of Fusarium oxysporum pathogen by 86.3, 85.9% and 78.2 %, respectively. In green house experiments, the data showed that the mixed application treatment (soil drench and foliar spray) is important for controlling Fusarium oxysporum pathogen. Thyme oil was less effective than the other treatments as biocontrol agent for the pathogen. The Highest determined chlorophyll content was determined in the treatment of T. harzianum (48.23), Chitosan® (47.66) and Top perfect® (44.97), without significant differences between T. harzianum and chitosan, especially in the mixed application treatment. Moreover, the treatments of Chitosan®, T. harzianum and Top perfect®, significantly, showed the highest fresh, dry weights and root length of plants and the least disease incidence and severity percentages compared with the untreated control.

MOLECULAR IDENTIFICATION OF FUNGI THE CAUSAL AGENT OF STRAWBERRY WILT DISEASE IN BALI

The development of strawberry farming in Bali experiencing some obstacles that cause a decline in production, such as wilting disease. The disease was reported caused by the fungi base on morphological recognition. There are two fungi were recognized caused the strawberry wilt disease in Bali, they are from genus Verticillium and Fusarium. More specific information about causal agent of wilt disease in strawberry especially in Bali is needed. The one accurate identification is done through the molecular approach by analyzing DNA that encode the ribosomal DNA (rDNA). The 18S rDNA, including the internal areas of transcribed spacers (ITS), ITS1 and ITS4 have been widely used in phylogenetic studies. The amplification results of this area produce bands in different sizes that can be used to identify fungal species. Based on that the identification of strawberry wilt disease using molecular analysis was conducted. The 542 bp of Internal Transcribed Spacer (ITS) DNA was successfully amplified using PCR with pairing primers ITS 1 (5-TCCGTAGGTGAACCTGCGG-3’), and ITS 4 (5’-TCCTCCGCTTATTGATATGC-3’). The sequences of three isolates were successfully obtained through sequencing. Homology levels were tested between sequences and showed that Candi Kuning sequence and Gobleg sequence had 95% similarity with sequence of Fusarium oxysporum NRRL 13307 (U34571) from America. While Pancasari sequence have 94% similarity with sequence of Fusarium oxysporum NRRL 13307 (U34571) from America. Candi Kuning, Gobleg, and Pancasari sequences had the same 86% with sequence of Fusarium oxysporum isolate C34-294 Brazil (KJ439088) and had 89% similarity with sequence Fusarium oxysporum f.sp. fragariae China (KT833080). Homology levels were tested between sequences and showed that Candi Kuning sequence and Gobleg sequence had 95% similarity with sequence of Fusarium oxysporum NRRL 13307 (U34571) from America. While Pancasari sequence have 94% similarity with sequence of Fusarium oxysporum NRRL 13307 (U34571) from America. Candi Kuning, Gobleg, and Pancasari sequences had the same 86% with sequence of Fusarium oxysporum isolate C34-294 Brazil (KJ439088) and had 89% similarity with sequence Fusarium oxysporum f.sp. fragariae China (KT833080). Based on phylogeny analysis of Pancasari, Gobleg and Candi Kuning isolates were obtained in one group with Fusarium oxysporum identified in America and Brazil, and also in one group with Fusarium oxysporum f. sp. fragariae that identified in China.

Proteomic analysis reveals the mechanisms involved in the enhanced biocontrol efficacy of Rhodotorula mucilaginosa induced by chitosan

The biocontrol efficacy of the yeast, Rhodotorula mucilaginosa against postharvest diseases of strawberries can be significantly enhanced by culturing the yeast in a medium containing chitosan. The molecular mechanisms involved in the enhanced biocontrol efficacy of R. mucilaginosa, however, have not been comprehensively explored. Results of the present study indicate that the biocontrol efficacy of the yeast against gray mold (Botrytis cinerea) of strawberry was greatest when the yeast was cultured in a medium containing 0.5% (w:v) chitosan for 24 h before use. Proteomic and bioinformatic analyses revealed that proteins involved in growth and reproduction, energy metabolism, antioxidant response, response to abiotic stress, and degradation of pathogen cell walls were all up-regulated by chitosan resulting in the enhanced antagonistic activity of R. mucilaginosa against B. cinerea. The decrease in ROS accumulation in R. mucilaginosa cultured in a medium containing chitosan was in agreement with the increased abundance of proteins related to antioxidant defense. Key differentially expressed proteins (DEPs) were identified and 12 randomly-selected DEPs were validated by parallel reaction monitoring. The present results provide a theoretical reference for further study of the molecular mechanisms involved in the improvement of biocontrol efficacy of antagonistic yeast by elicitor molecules and also provide a novel approach for improving biological control of postharvest diseases.

A novel endophytic strain of Lactobacillus plantarum CM-3 with antagonistic activity against Botrytis cinerea on strawberry fruit

The fungal pathogen Botrytis cinerea causes grey mold, a severely damaging disease of strawberry. Lactic acid bacteria (LAB) are known for their biopreservative activity. Meanwhile, LAB dominate in plant organs over time, and are of pivotal importance for plant defense. The goal of the present study was to isolate endophytic LAB and to evaluate for their biocontrol activities against B. cinerea. Of the tested endophytic bacteria isolates, Lactobacillus plantarum CM-3 demonstrated the highest potential for in vitro and in vivo control of B. cinerea. The in vitro results showed that L. plantarum CM-3 reduced the mycelial growth of B. cinerea on Potato Dextrose Agar (PDA) between 55.27% and 79.80%. Spore germination of the pathogen was greatly inhibited in the presence of living cell suspensions. In in vivo biocontrol assays, the decay incidence and lesion diameter of grey mold decay of strawberries treated by L. plantarum CM-3 cells were significantly (P < 0.05) reduced compared with the control fruit. At concentrations of 1 × 108 and 1 × 109 CFU mL−1, the incidence of gray mold was reduced by 48.23% and 75.00% respectively, compared to the control, after storage at 20 °C for 6 d. Moreover, rapid colonization of L. plantarum CM-3 in wounds was observed both in the presence or absence of B. cinerea at 20 °C during the storage period. The concentrations of the antagonist had significant effects on biocontrol effectiveness both in vitro and in vivo. However, cell-free filtrates of the strain failed to provide any protection against B. cinerea. Findings of the present study suggested that L. plantarum CM-3 could be a promising biocontrol agent for application during the post-harvest storage and marketing of horticultural products. This study reports the first assessment of endophytic LAB isolated from strawberry fruit and selection of isolates for the biocontrol of B. cinerea.

Aplicação foliar de silício reduz a ocorrência de doenças fúngicas na cultura do morangueiro

Diversas doenças fúngicas podem ocorrer na cultura do morangueiro, dentre as quais, a micosferela, a antracnose e o mofo cinzento. O silício é um mineral que atua como agente fertilizante e defensivo agrícola. A fim de reduzir o uso de agrotóxicos, esse trabalho teve por objetivo avaliar o efeito de diferentes doses de silício no controle das principais doenças fúngicas do morangueiro cultivado no Planalto Norte Catarinense. O trabalho foi realizado na área experimental do IFSC – Campus Canoinhas, através de tratamentos que consistiram na aplicação de cinco diferentes doses de silício, por meio do produto Agrisil® (99% Si). Foram realizadas aplicações com diferentes doses do produto, 100, 200, 300 e 400 g (i.a. silício)/100L água. As avaliações da incidência e severidade das doenças foram realizadas, e as doses de 300g e 400 g (i.a. silício)/100L água proporcionaram redução na ocorrência da micosferela e mofo cinzento. Assim, o uso de silício apresenta-se como uma alternativa para o controle dessas doenças, reduzindo os impactos ambientais e o efeito nocivo ao trabalhador rural.

Common Strawberry Diseases in Florida

This publication describes symptoms of most common strawberry diseases in Florida and summarizes the efficacy of fungicides labeled for management of such diseases.

PHYLOGENETIC ANALYSIS OF FUSARIUM OXYSPORUMF STRAINS ISOLATED FROM STRAWBERRY CROPSFRAGARIA ANANASSADUCH IN THE PROVINCE OF PICHINCHA (ECUADOR)

Objective: Strawberry cultivation has acquired great importance for consumption, promoting the increase of its production in Ecuador. However, the process of importing plant material from producing countries in order to improve domestic production has contributed to the dissemination of the fungus Fusarium oxysporum f. sp. fragariae.&#x0D; To identify the presence of the pathogen, by applying molecular techniques to the Fusarium strains isolated from strawberry crops.&#x0D; Methods: Nine two diseased strawberry plants and 92 asymptomatic plants were analyzed. From these samples, 13 fungi with the characteristics of the Fusarium genus were identified. The isolates were analyzed at the molecular level, by PCR (Polymerase chain reaction) amplifying the ITS regions of the rDNA and the EF-1α region.&#x0D; Results: The PCR product was sequenced to elucidate the phylogenetic relationships between the isolates, identifying 12 strains as F. oxysporum f. sp. fragariae. These results confirmed the presence of the fungus in the strawberry crops analyzed, representing a contribution to the search for control alternatives to avoid the spread of the pathogen.&#x0D; Conclusion: The PCR product was sequenced to elucidate the phylogenetic relationships between the isolates, identifying 12 strains as F. oxysporum f. sp. fragariae.

Strawberry resistance to the major fungal phytopathogens: R-genes and their DNA markers

The garden strawberry Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier (1785) is a perennial herbaceous plant of the Rosaceae family; it is cultivated all around the world. It accounts for more than half of the global volume of berries production. In Russia, more than 160 tons of garden strawberries are grown annually, but according to Russian scientists, this crop has a much higher productivity potential. Various pathogens, including bacterial, viral and fungal infections, negatively affect the productivity of strawberry. Anthracnose (caused by Colletotrichum Corda . ), crown rot ( Phytophthora cactorum Lebert & Cohn), red core disease ( Phytophthora fragariae var. fragariae Hickman), fusarium wilt ( Fusarium oxysporum f. sр. fragariae Winks & Williams ) and strawberry powdery mildew ( Podosphaera aphanis [ Sphaerotheca macularis ] (Wallr.) U. Braun & S. Takam) are among the most important fungal diseases of strawberry. This review discusses the current data about the known genes and quantitative trait loci (QTLs) associated with resistance to listed plant pathogens. The review also offers information about molecular markers of different types: SDRF, AFLP, SSR, SCAR, SNP, associated with these genes/QTLs and used in the molecular screening of strawberry collections for practical purposes.

Genetic diversity of strawberry mild yellow edge virus from eastern Canada.

Strawberry mild yellow edge virus (SMYEV) is a member of the genus Potexvirus, family Alphaflexiviridae. It is one of the most common pathogenic viruses infecting cultivated strawberries worldwide. In this study, we investigated the genetic diversity of SMYEV in strawberry fields that were severely affected by strawberry decline disease in the eastern Canadian provinces of New Brunswick, Nova Scotia, Prince Edward Island and Quebec. A total of 134 SMYEV coat protein (CP) gene sequences, representing 85 nucleic acid haplotypes, were identified in 56 field samples. A highly divergent SMYEV population was found in all four provinces, but there was little genetic differentiation among the populations, and moreover, the Canadian SMYEV isolates formed a unique dissimilar, genetically divergent population group when compared to those reported in other countries. Phylogenetic analysis revealed three new SMYEV subclades that consisted mainly of Canadian variants and were composed of 76 sequence haplotypes (76/85, 88%). Mixed infections by different SMYEV variants were observed in 38 samples (38/56, 68%). Evolutionary analysis suggested that the SMYEV strains in eastern Canada possibly originated outside of Canada but adapted to conditions in the region through genetic mutations.

Dominant fungal diseases of garden strawberries (Fragaria ananassa Duch.) within the territory of Ukraine

Today, the area under strawberries is growing every year. Because it is valued for its unpretentiousness to soil conditions, early and rapid fruit ripening, stable yields and resistance to low temperatures. But researchers note a reduction in yields in areas occupied by industrial strawberry plantations in horticultural farms due to the negative impact of the spread of fungal diseases. Gray mold (Botrytis cinerea Pers), verticillium wilt (Verticillium albo-atrum Reinke et Berth.), white spot (Ramularia tulasnei Sacc) and brown spot (Marssonina potentillae P. magn. f. Fragaria Man.), late wilting (Phytophthora fragariae Hick), late blight (Phytophthora cactorum (Leb. et Cohn.) are the dominant fungal diseases of garden strawberries in Ukraine. White spot affects the leaves, petioles, peduncles, sepals and stalks of garden strawberries. When affected by the disease, the appearance of reddish-brown spots is observed, which eventually acquire a white color and a dark red rim appears around. Brown spot mainly damages the leaves of strawberries, which affects the photosynthesis of the plant. Signs of this disease are the appearance of light olive spots, which later turn yellow, and on the underside of the leaf a plaque from light gray to green-brown color is formed. Gray mold fungus affects the leaves, flowers and fruits of garden strawberries. A "fluff" of conidia is formed on berries. They soften, change color to brown and rot. Infection of strawberries with verticillium wilt occurs through the root system. After penetration of the pathogen into the plant, the formation of chlorotic spots is observed. Eventually, the leaves turn yellow, dry up, the conductive tissues are destroyed and the plant dies. Two forms of phytophthora wilting of garden strawberries are described. In the first form, the color of the leaves changes from red to yellow-brown, which then withers and dries. The plant itself lags behind in growth. The second form of the disease affects the root system. The roots turn gray or brown and die. Signs of late blight rot are visible on the roots of strawberries in late autumn, and on the aboveground organs in the spring. Brown ring spots are formed on the root neck, which turn into rot. Necrosis appears on the stem and veins of the leaves, after which the young leaves slow down their growth and dry up. When the plant is affected by pathogens, there is a decrease in yield: white spot causes 10–30 %, brown spot – up to 50 %, gray mold – 30 %, wilting (late blight, verticillium wilt) and late blight – up to 50–60 %. Therefore, since fungal diseases cause a decrease in yield and quality of the species composition of strawberries, it is necessary to develop a system of protection, using agronomic, biological and chemical methods of control.

Biological control of strawberry grey mold disease caused by Botrytis cinerea mediated by Colletotrichum acutatum extracts

Despite the negative impact on human, animal and environmental health, synthetic fungicides are the most common agrochemicals used to control Botrytis cinerea, the causal agent of grey mold disease. Strawberry plants are very susceptible to many pathogens, especially the necrotrophic fungus B. cinerea. In this work, we show that two fungal extracts obtained from a local isolate of Colletotrichum acutatum (M11) can protect strawberry plants against grey mold. Fungal culture filtrate (CF), and the axenic semi-purified culture filtrate (ACF) induce local and systemic acquired resistance against B. cinerea, and reduce fungal virulence. These results suggest that CF and ACF can be used as effective ingredients of bioproducts to control grey mold in strawberry crop. We also show that the elicitor peptide flg22 is effective to confer strawberry plants local and systemic protection against B. cinerea but only when applied 24 h prior to the infection.

A novel strain of endophytic Streptomyces for the biocontrol of strawberry anthracnose caused by Glomerella cingulata

Anthracnose caused by Glomerella cingulata is one of the most devastating diseases of strawberry in Japan, particularly during its nursery period in the summer. In this study, we aimed to isolate and screen endophytic actinobacteria, to identify potential biocontrol agents capable of suppressing strawberry anthracnose. A total of 226 actinobacteria were successfully isolated from surface-sterilized strawberry tissues. In the first screening, 217 out of 226 actinobacteria isolates were studied for their suppression effect on strawberry anthracnose using a detached leaflet assay. It was discovered that isolates MBFA-172 and MBFA-227 markedly suppressed the development of anthracnose lesions. The efficacy of both isolates was then tested on two-month-old strawberry plug seedlings in a controlled environmental chamber. It was found that isolate MBFA-172 provided consistent disease suppression and was thus selected as a final candidate for further evaluation in a glasshouse experiment. Results showed that the severity as well as incidence rate of strawberry anthracnose was significantly reduced by treatment with isolate MBFA-172 compared with that of untreated control. Accordingly, the disease control efficacy provided by MBFA-172 was statistically comparable to the chemical fungicide propineb. A re-isolation experiment using a spontaneous thiostrepton-resistant mutated strain of isolate MBFA-172 revealed that it efficiently colonized the above-ground tissues of strawberry plants for at least three weeks after spray treatment. Using cultural, morphological, and physiological tests combined with 16S rRNA-based molecular analysis, MBFA-172 was identified as a moderately thermophilic Streptomyces thermocarboxydus-related species. Upon review, our results strongly indicated that MBFA-172 is a promising biocontrol agent for strawberry anthracnose.

Innovation of fruit coating with antifungal yeast to maintain the quality of postharvest strawberries

Postharvest strawberries have a relatively short shelf life and the quality of fruit is rapidly declining, especially with a history of high gray mold fungus attacks during cultivation in the garden. The attack rate of fruit rot is high in the garden, causing the surface of strawberries to be colonized by pathogenic spores which results in strawberries becoming susceptible to postharvest disease. One of the main diseases of postharvest strawberries is gray mold rot caused by Botrytis cinerea. Fruit coating is one of the innovations used to extend shelf life and maintain the quality of fruit stored at room temperature. Coating of fruit with natural ingredients is still little researched, especially made from yeast. The aim of the study was to determine the effectiveness of coating postharvest strawberries with antifungal yeast at various levels of maturity on the quality and shelf life of strawberries. The results showed coating strawberries with yeast Debaryomyces hansenii was able to maintain the quality of the fruit, increase the shelf life of the fruit, and protect the fruit from the attack of postharvest pathogens with parasitism mechanism, without reducing the quality of fruit, so that it can be applied after the harvest of strawberries.

Dimethyl disulfide (DMDS), straight and in combined fumigant applications, to control strawberry soil disease complex in Spain

Dimethyl disulfide (DMDS), straight and in combined fumigant applications, to control strawberry soil disease complex in Spain

Biocontrol of Fusarium wilt disease in strawberries using bioorganic fertilizer fortified with Bacillus licheniformis X-1 and Bacillus methylotrophicus Z-1.

Fusarium wilt caused by Fusarium oxysporum f. sp. fragariae is one of the most serious indigenous soil-borne fungal disease of strawberry. In this study, we have identified and investigated two sets of bacterial samples: Bacillus licheniformis (X-1) and Bacillus methylotrophicus (Z-1). Both of them were isolated from the rhizosphere soil of healthy strawberries which showed a strong inhibitory effect on Fusarium wilt caused by Fusarium oxysporum f. sp. fragariae. Bioorganic fertilizer developed by our team exhibiting a strong inhibition ability against the pathogen in comparison with the chemical and organic fertilizers. It allowed 80% disease free strawberry production together with improved physical and biochemical indexes in the pot experiments. The enzyme activity analysis of SOD, PPO, POD, and CAT in the bioorganic fertilizer (BOF) group showed significant increase with values; 48.8%, 68.7%, 85.9%, and 41.1% than that of the control group, respectively. The results of bacterial diversity showed that Bacillus in group BOF was almost three times as large as in the healthy soil control group (CK). Besides, the results of microbial diversity showed that Fusarium and Fusicolla of BOF was nearly five times less than that in CK and chemical fertilizer groups, where the Bacillus content reached to three times as much of the CK. Moreover, the enzymes activity and the content of beneficial microorganisms in the rhizosphere increased significantly. In this study, the bioorganic fertilizer developed by the isolated strains had significant effects on the control of strawberry Fusarium wilt disease. Our results demonstrate that BOF is a promising approach to control this disease in strawberry production.

Management of Strawberry Anthracnose Using Plant Essential Oils as Bio-fungicides, and Evaluation of Their Effects on Quality of Strawberry Fruit.

Colletotrichum nymphaeae is the causal agent of strawberry anthracnose, which is one of the most important disease affecting strawberry plant in Iran. This research aimed to apply the selected plant essential oils (EOs) such as Achillea millefolium, Mentha longifolia, and Ferula kuma to the management of strawberry anthracnose disease under in vitro, in vivo, and greenhouse conditions. In vitro tests indicated that all the EOs and fungicide were able to inhibit mycelial growth and conidial germination of the pathogen. Scanning electron microscopy (SEM) revealed that EOs significantly suppressed the mycelia growth and caused a change in morphology of fungal mycelia. The severity of strawberry anthracnose disease was significantly (p ≤ 0.05) reduced by all EOs under in vivo and greenhouse conditions. Results of all experiments showed that M. longifolia EO was the best EO to control C. nymphaeae. Also, EOs almost reduced weight loss and preserved firmness, ascorbic acid, total phenol, antioxidant activity (DPPH), and enzyme peroxidase activity in treated fruit. Moreover, EOs preserved the sensory quality of strawberry fruit during the storage period so that there were no significant differences between treatments (EOs) in their appearance, flavor, odor attributes, and overall evaluation compared to the control. Our results indicate that EOs are excellent bio-fungicides for the management of strawberry anthracnose.

Review on agro-nanotechnology for ameliorating strawberry cultivation

Strawberry production is appreciated in all over the world because of its attractive fruits and nutritional characteristics. It is of great commercial value, in this study, we reviewed and investigated using agro-nanoparticle based products and their application for managing strawberry fungal disease. The use of nanotechnology technique in materials science and biomass conversion technologies used in the agricultural sector is fundamental in the production of food, feed and fuels. The demand for food is projected to increase exponentially in the near future, while natural resources such as land, water and soil fertility are limited. Indiscriminate application of chemicals causes environmental pollution, emergence of resistant agricultural pests, pathogens and loss of biodiversity. Nanoparticle production has received great attention from chemists and biologists who wish to use them for developing a new generation of nano fertilizers and nano pesticides. Synthesis of nanoparticles involves several numbers of chemicals, and biological methods consisting chemical reduction in aqueous or non-aqueous solution, micro emulsion, template, chemical and microwave assisted. Using nanoparticles in plant growth and for controlling diseases is a rather recent phenomenon. Nonetheless, trends in research have been moving towards exploring the biological effects of nanoparticles on higher plants.

Efficacy of soil solarization on black root rot disease and speculation on its leverage on nematodes and weeds of strawberry in Egypt

BackgroundStrawberry (Fragaria ananassa Duch.) is an economically important crop in Egypt. Yet complex black root rot disease of strawberry caused by Fusarium solani, Rhizoctonia solani, and Pythium sp. can cause considerable yield losses. Therefore, this study aimed at evaluating different aspects of soil solarization against this disease. Such an evaluation would better be viewed in the context of other beneficial effects of soil solarization on nematodes and weeds.Materials/methodsGrowth agar disks, growth suspension, and resting stages of strawberry black root rot fungi were evaluated at different temperatures and exposure times using digital hot water bath. Cloth bags artificially infested with single fungal species were buried into the soil before soil solarization at soil depths of 1–10, 11–20, and 21–30 cm at three spots of each plot for each of the abovementioned fungi for 3, 6, or 9 weeks. The disease incidence and severity in solarized and un-solarized soil was compared with the application of the fungicide Actamyl. Effects of soil solarization on nematodes and weeds were also consulted.ResultsThe lethal temperature to F. solani, Pythium sp., and R. solani was 58, 58, and 56 °C, respectively when exposure time was 1 min. Chlamydospores were killed at 62 °C while sclerotia were killed at 58 °C in hot water for 1 min. Maximum soil temperature in solarized soil was raised by 15, 14, and 12 °C at depths of 1–10, 11–20, and 21–30 cm as compared with non-solarized soil. Solarization for 3, 6, and 9 weeks significantly reduced the disease incidence and severity and increased the strawberry yield. Complete reduction in total count of all tested fungi was obtained after 9 weeks at all tested depths. A review of collective soil pest and pathogen control via solarization documented its beneficial application.ConclusionThe study may exploit hot months in Egypt for soil solarization against the serious root rot disease either singly or in an integrated pest management program.

Local Trichoderma strains as a control strategy of complex black root rot disease of strawberry in Egypt

BackgroundEconomics and human safety to avoid health risks caused by fungicides are materializing new era of biological pest control. Trichoderma species ranked high among other agents to control complex black root rot disease of strawberry caused by Fusarium solani, Rhizoctonia solani, and Pythium sp. Our study aimed to document the efficacy of local strains representing T. harzianum, T. viride, T. virinis, and T. koningii against such a disease.Materials/methodsThese strains were cultured separately on potato dextrose broth medium to test their inhibitory effect against strawberry black root rot in vitro and in vivo. Strawberry growth and yield were also assessed relative to the untreated check and the fungicide Actamyl. Activity of peroxidase and chitinase were measured in plant leaves using spectrophotometer.ResultsEach of the antagonistic fungal strains significantly reduced growth area of all pathogenic fungi collectively causing the disease. Trichoderma harzianum, T. viride, and T. koningii reduced the growth area more than 90.6% for all tested pathogenic fungi. Each species significantly reduced disease incidence and severity under field conditions. The highest reduction in the disease incidence and severity, 83.3 and 88.5% respectively, was attained by mixture of the four species. This mixture increased the strawberry fresh and dry weight by 83.3 and 176.9%, respectively, and the yield by 117.1%. All Trichoderma species tested significantly increased the activity of two plant defense-related enzymes of strawberry plants against the pathogens. Their mixture attained the highest increase of peroxidase and chitinase activity by 150 and 160.9%, respectively.ConclusionsWhile the fungal mixture could considerably increase the strawberry fresh and dry weight as well as the yield, it suppressed the incidence and severity of the disease. So, integrated pest management in ways that make these biocontrol agents complementary or superior to chemical fungicides should further be examined against this disease.