Clonostachys rosea to control plant diseases

The fungus Clonostachys rosea was recognized as an aggressive parasite on other fungi already in the late 1950s. Research into its potential use in biological control of plant diseases soon followed. Today, there are several commercial products based on C. rosea available for biocontrol applications worldwide. Although its mycoparasitic ability has attracted a lot of interest, C. rosea is now viewed as an ecological generalist whose lifestyle also includes plant endophytism, rhizosphere competence and polyphagous ability. Protocols for producing high amounts of C. rosea spores are available for both solid state and liquid fermentation. Low temperature and low moisture content are key factors that influence the shelf life of C. rosea propagules. Products based on C. rosea can be delivered to flowers using bumble bees, applied by spraying or as seed dressing or by incorporation into the soil. Clonostachys rosea is today an established factor in sustainable plant protection strategies.

A Comparison of the Ability of Some Commercially Produced Biological Control Agents to Protect Strawberry Plants against the Plant Pathogen Phytophthora cactorum

A comparison of the ability of commercially produced biological control agents—Contans, Gliorex, Hirundo, Polyversum, Prometheus, Clonoplus, Integral Pro and Xilon GR, completed with an isolate of Clonostachys rosea and of Pseudomonas sp.—to protect strawberry plants against Phytophthora cactorum was performed. The experiment was performed on strawberry cultivars Sonata, Karmen, and Wendy—cultivated in a cultivating room and greenhouse. The health of plants was affected negatively by the pathogen in all variants of biological agents used, but differences were seen in the rates of this decrease. The results revealed the ability of some tested agents to improve the growth of plants in the absence of the pathogen; the preparation Polyversum (Pythium oligandrum) was the most beneficial, in both the presence and absence of the pathogen. Contrarily, some agents alone decreased the health of plants; Integral Pro (Bacillus subtillis) and a strain of Pseudomonas sp. caused a deterioration in the health of the plants, even in the absence of a pathogen. The results of our analysis demonstrate the varied usefulness of all agents under unified environmental conditions; their effect seems to be dependent on the conditions and on the combination of the genotypes of all three participants in the interaction: plant–pathogen–antagonist.

Untangling the Pea Root Rot Complex Reveals Microbial Markers for Plant Health

Plant health is recognised as a key element to ensure global food security. While plant breeding has substantially improved crop resistance against individual pathogens, it showed limited success for diseases caused by the interaction of multiple pathogens such as root rot in pea (Pisum sativum L.). To untangle the causal agents of the pea root rot complex and determine the role of the plant genotype in shaping its own detrimental or beneficial microbiome, fungal and oomycete root rot pathogens, as well as previously identified beneficials, i.e., arbuscular mycorrhizal fungi (AMF) and Clonostachys rosea, were qPCR quantified in diseased roots of eight differently resistant pea genotypes grown in four agricultural soils under controlled conditions. We found that soil and pea genotype significantly determined the microbial compositions in diseased pea roots. Despite significant genotype x soil interactions and distinct soil-dependent pathogen complexes, our data revealed key microbial taxa that were associated with plant fitness. Our study indicates the potential of fungal and oomycete markers for plant health and serves as a precedent for other complex plant pathosystems. Such microbial markers can be used to complement plant phenotype- and genotype-based selection strategies to improve disease resistance in one of the world’s most important pulse crops of the world.

Selection of bacteria and fungi for control of soilborne seedling diseases of maize

Plant-based screening experiments were conducted with the aim of identifying biocontrol bacteria and fungi for seed treatment of maize. Candidate microorganisms were evaluated for their protective effects against soilborne infections by species of Fusarium, Globisporangium (syn. Pythium) and Rhizoctonia. The microorganisms tested were bacteria and fungi from maize roots or other sources, including some active microbial components of commercial biocontrol products. Due to the method of isolation chosen, the majority of bacteria from maize roots were spore formers, most of them species of the genera Bacillus,Brevibacillus and Paenibacillus. In pot tests with the potting substrate inoculated with F. culmorum, the level of control provided by seed treatment with the most efficacious bacterial and fungal isolates was comparable or close to the chemical reference seed treatment thiram. The most effective bacteria were species of Pseudomonas, Burkholderia and Streptomyces. Among a subset of approx. 100 bacteria studied, the in vivo and in vitro activities against F.culmorum were only weakly correlated, although some strains deviated from this pattern. The most effective fungi were two strains of Clonostachys rosea and isolates of Trichoderma. The latter and a strain of Gliocladium virens provided also protection against R.solani. Activity against Globisporangium ultimum was recorded for one isolate of Trichoderma and the two strains of C. rosea. A reduction in the impact of seedborne F. culmorum was also observed after seed treatment with two strains of F. oxysporum f. sp. strigae. The results are discussed in relation to previous reports on rhizosphere bacteria of maize and their use in biocontrol of plant pathogens or for plant growth promotion.

اختبار التضاد الفطري بين الفطرين الاحيائيين Trichoderma harzianum وT.viride وبعض الفطريات الصائدة للنيماتود على الاوساط الصلبة

تم اختبار القدرة التضادية بين الفطرين الأحيائيين Trichoderma harzianum وT. viride مع سبعة أنواع من الفطريات الصائدة للنيماتود (Arthrobotrys oligospora و A.conoides و A.eudermata و A.thaumasia و A.microcaphoides و A.cookedichison و Clonostachys rosea) على الوسطين وسط بطاطا - دكستروز- أكار (PDA) ووسط أكار- خلاصة الذرة (CMA). أظهرت النتائج ان الفطرين T. harzianum و T. viride يمتلكان قدرة تضادية عالية ضد الفطريات الصائدة للنيماتود المختبرة ، ووجد ان الفطر T. harzianum له تضاد ضد الفطريات الصائدة المختبرة أفضل من الفطر T.viride ، وبينت الدراسة ان الفطرين T.harzianumو T.viride لهما درجة تضاد 1، 2، 3 حسب مقياس Bell et al., (1982). كانت أكثر درجة تضاد هي 2 للفطرين T. harzianum و T. viride مع أغلب الفطريات المدروسة على الوسطين CMA وPDA. أظهرت النتائج انه لا يوجد اختلاف واضح في درجة التضاد عند استخدام الوسطين الزرعيين CMA وPDA عدا بعض الفطريات التي كان تضادها اختلف بين الوسطين الزرعيين. ولوحظ ان الفطر T. harzianum كانت درجة تضاده 1 مع الفطر A. conoidesوعلى الوسطين CMA و PDA والفطر A.thaumasia على الوسط CMA، في حين ان الفطر T.viride اعطى نفس الدرجة مع الفطر A.eudermata على الوسط PDA