The loss of organic material from the roots provides the energy for the development of active microbial populations in the rhizosphere around the root. Generally, saproptrophs or biotrophs such as mycorrhizal fungi grow in the rhizosphere in response to this carbon loss, but plant pathogens may also develop and infect a susceptible host, resulting in disease. This review examines the microbial interactions that can take place in the rhizosphere and that are involved in biological disease control. The interactions of bacteria used as biocontrol agents of bacterial and fungal plant pathogens, and fungi used as biocontrol agents of protozoan, bacterial and fungal plant pathogens are considered. Whenever possible, modes of action involved in each type of interaction are assessed with particular emphasis on antibiosis, competition, parasitism, and induced resistance. The significance of plant growth promotion and rhizosphere competence in biocontrol is also considered. Multiple microbial interactions involving bacteria and fungi in the rhizosphere are shown to provide enhanced biocontrol in many cases in comparison with biocontrol agents used singly. The extreme complexity of interactions that can occur in the rhizosphere is highlighted and some potential areas for future research in this area are discussed briefly.

/pdf/microbial-interactions-and-biocontrol-in-the-rhizosphere-1erj9kqzek.pdf

Microbial interactions and biocontrol in the rhizosphere

Although the number of biocontrol products is increasing, these products still represent only about 1% of agricultural chemical sales. Yet these are important contributions because biocontrol agents offer disease management alternatives with different mechanisms of action than chemical pesticides. Trends in research include the increased use of biorational screening processes to identify microorganisms with potential for biocontrol, increased testing under semicommercial and commercial production conditions, increased emphasis on combining biocontrol strains with each other and with other control methods, integrating biocontrol into an overall system.

Commercialization and Implementation of Biocontrol 1

Herbs, spices and their active components as natural antimicrobials in foods Effect of natural antioxidants in herbs and spices on shelf life of foods Ajowan Aniseed Asafoetida Allspice Capers and caperberries Caraway Celery Chervil Fennel and fennel seed Galangal Kaffir lime leaf Lavender Lemongrass Lovage Nigella Oregano Poppy Sesame Star anise Tarragon Tamarind Other significant herbs and spices.

Handbook of Herbs and Spices

Plant growth-promoting rhizobacteria (PGPR) strains INR7 (Bacillus pumilus), GB03 (Bacillus subtilis), and ME1 (Curtobacterium flaccumfaciens) were tested singly and in combinations for biological control against multiple cucumber pathogens. Investigations under greenhouse conditions were conducted with three cucumber pathogens-Colletotrichum orbiculare (causing anthracnose), Pseudomonas syringae pv. lachrymans (causing angular leaf spot), and Erwinia tracheiphila(causing cucurbit wilt disease)-inoculated singly and in all possible combinations. There was a general trend across all experiments toward greater suppression and enhanced consistency against multiple cucumber pathogens using strain mixtures. The same three PGPR strains were evaluated as seed treatments in two field trials over two seasons, and two strains, IN26 (Burkholderia gladioli) and INR7 also were tested as foliar sprays in one of the trials. In the field trials, the efficacy of induced systemic resistance activity was determined against introduced cucumber pathogens naturally spread within plots through placement of infected plants into the field to provide the pathogen inoculum. PGPR-mediated disease suppression was observed against angular leaf spot in 1996 and against a mixed infection of angular leaf spot and anthracnose in 1997. The three-way mixture of PGPR strains (INR7 plus ME1 plus GB03) as a seed treatment showed intensive plant growth promotion and disease reduction to a level statistically equivalent to the synthetic elicitor Actigard applied as a spray.

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/PHYTO.1998.88.11.1158

Mixtures of Plant Growth-Promoting Rhizobacteria Enhance Biological Control of Multiple Cucumber Pathogens

Integrated management strategies of bean root rot with Bacillus subtilis and Rhizobium in Minnesota

Aerial blight, caused by Rhizoctonia solani AG-4, was identified as a major disease of greenhouse mist-produced rosemary cuttings. An isolate of the biocontrol fungus Laetisaria arvalis, selected for tolerance to the experimental fungicide CGA 173506, was used as an amendment to potting soil. Combined treatment of rosemary with L. arvalis and a foliar spray of the fungicide at one-half the recommended rate reduced disease more than treatment with either the fungus or fungicide alone. Similar synergism was not observed for combinations of Trichoderma harzianum as a soil amendment and a foliar spray of the fungicide iprodione applied at the labeled rate.

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/PDIS.1997.81.7.795

Integration of biological and chemical controls for Rhizoctonia aerial blight and root rot of rosemary

Peroxidase activity is used by the food processing industry as an indi- cator of adequacy of the blanching process and to predict off-flavour develop- ment in frozen food. Research reported herein showed that total peroxidase activity did not parallel flavour changes in frozen unblanched supersweet (sh2) or sugary enhanced (sullse) sweet corn genotypes. Frozen corn-on-the-cob of 'Florida Staysweet' (sh2), 'Merit' (standard sweet-sul) and 'Bodacious' (sullse), blanched and unblanched, was subjected to sensory evaluation and peroxidase analysis following frozen storage up to 12 months. Trained taste panellists rated the unblanched sh2 and sullse corn as acceptable up to 8 months of frozen storage. Kernels were cut from cobs after 0 and 12 months of storage. Proteins were extracted from acetone powders of kernels and separated by isoelectric focusing and native PAGE. Banding patterns differed according to genotype and storage duration. These results suggested molecular differences in peroxidase iso- zymes among the sweet corn genotypes which could be involved in off-flavour development. All genotypes contained a peroxidase isozyme having a molecular mass of 80 kDa and PI of 4-5. The sullse and sh2 genotypes produced an addi- tional peroxidase band of 13.8 kDa. An additional peroxidase isozyme (PI 5.4) appeared in extracts from the sul genotype after 12 months storage. Although changes in total peroxidase activity may not predict flavour changes in all geno- types, the presence or absence of certain peroxidase isozymes may be useful in predicting off-flavour development in sul frozen corn.

/pdf/flavour-qualities-of-frozen-sweetcorn-are-affected-by-3fvoypmf3a.pdf

Flavour Qualities of Frozen Sweetcorn are Affected by Genotype and Blanching

/pdf/resistance-in-muskmelon-cultivars-to-melon-aphid-2y0hggzmoh.pdf

Resistance in muskmelon cultivars to melon aphid

https://journals.ashs.org/downloadpdf/journals/hortsci/26/5/article-p487e.pdf

N. Maness

Papers

Integration of biological and chemical controls for Rhizoctonia aerial blight and root rot of rosemary

Flavour Qualities of Frozen Sweetcorn are Affected by Genotype and Blanching

Resistance in muskmelon cultivars to melon aphid

Propagating rosemary (rosemarinus officinalis) by cuttings

Will secondary buds be savior to pecan spring freeze damages?