Antagonistic Strain Bacillus amyloliquefaciens XZ34-1 for Controlling Bipolaris sorokiniana and Promoting Growth in Wheat

Common root rot, caused by Bipolaris sorokiniana, is one of the most prevalent diseases of wheat and has led to major declines in wheat yield and quality worldwide. Here, strain XZ34-1 was isolated from soil and identified as Bacillus amyloliquefaciens based on the morphological, physiological, biochemical characteristics and 16S rDNA sequence. Culture filtrate (CF) of strain XZ34-1 showed a high inhibition rate against B.sorokiniana and had a broad antifungal spectrum. It also remarkably inhibited the mycelial growth and spore germination of B. sorokiniana. In pot control experiments, the incidence and disease index of common root rot in wheat seedlings were decreased after treatment with CF, and the biological control efficacy was significant, up to 78.24%. Further studies showed XZ34-1 could produce antifungal bioactive substances and had the potential of promoting plant growth. Lipopeptide genes detection with PCR indicated that strain XZ34-1 may produce lipopeptides. Furthermore, activities of defense-related enzymes were enhanced in wheat seedlings after inoculation with B.sorokiniana and treatment with CF, which showed induced resistance could be produced in wheat to resist pathogens. These results reveal that strain XZ34-1 is a promising candidate for application as a biological control agent against B.sorokiniana.

A Survey Report of Disease Fields of District; Swabi, Buner, Haripur and Mardan Province of Khyber Pakhtunkhwa

A survey of diseased fields of total (35) areas located in four different Districts of Khyber Pakhtun Khwa like Buner (4 areas), Swabi (23 areas) Mardan (3 areas) and Haripur (5areas) was carried out for estimation of losses and identification of root disease causing pathogens in 14 different economically important crops like Tobacco (Nicotiana tabacum), Ladyfinger (Abelmoscus esculentus), Chilli (Capsicum anuum), Eggplant (Solanum melongena), Maize (Zea mays), Tomato (Solanum lycopersicum), Wheat (Triticum estivum), Garlic (Allium sativum), Mustard (Brassica compestres), Clover (Trifolium repens), Onion (Allium cepa), Turnip (Brassica rapa), Radish (Raphanus sativus) and Pea (Pisum sativum). The most common root rot pathogens found in all the areas visited were Alternaria alternate, A.solani, Rhizoctonia solani Macrophomina phaseolina and species of Fusarium viz., Fusarium solani and F.oxysporum. Two species of root-knot nematode Meloidogyne javanica and M. incognita were also found causing root- knot disease. The eggplant was found upto 20-76% losses when an infection caused by the combined effect of F. oxysporum, M.phaseolina. R. solani and root-knot nematodes. Similarly, the loss of chiliplants was found 40-65% due to the combined effect of F. solani, M.phaseolina, R. solani, and root-knot nematodes. Zea mays crops were reported 50-77% losses due to Drecslera spp, F.solani, and A. solani Losses recorded by these root-rot and root-knot pathogens were found variable depending upon a combination of pathogens, temperature and soil types.

Genetics of Resistance to Common Root Rot (Spot Blotch), Fusarium Crown Rot, and Sharp Eyespot in Wheat

Due to soil changes, high density planting, and the use of straw-returning methods, wheat common root rot (spot blotch), Fusarium crown rot (FCR), and sharp eyespot (sheath blight) have become severe threats to global wheat production. Only a few wheat genotypes show moderate resistance to these root and crown rot fungal diseases, and the genetic determinants of wheat resistance to these devastating diseases are poorly understood. This review summarizes recent results of genetic studies of wheat resistance to common root rot, Fusarium crown rot, and sharp eyespot. Wheat germplasm with relatively higher resistance are highlighted and genetic loci controlling the resistance to each disease are summarized.

Bipolaris sorokiniana-Induced Black Point, Common Root Rot, and Spot Blotch Diseases of Wheat: A Review

Wheat is among the ten top and most widely grown crops in the world. Several diseases cause losses in wheat production in different parts of the world. Bipolaris sorokiniana (teleomorph, Cochliobolus sativus) is one of the wheat pathogens that can attack all wheat parts, including seeds, roots, shoots, and leaves. Black point, root rot, crown rot and spot blotch are the main diseases caused by B. sorokiniana in wheat. Seed infection by B. sorokiniana can result in black point disease, reducing seed quality and seed germination and is considered a main source of inoculum for diseases such as common root rot and spot blotch. Root rot and crown rot diseases, which result from soil-borne or seed-borne inoculum, can result in yield losses in wheat. Spot blotch disease affects wheat in different parts of the world and cause significant losses in grain yield. This review paper summarizes the latest findings on B. sorokiniana, with a specific emphasis on management using genetic, chemical, cultural, and biological control measures.

Efficacy of Bacillus SPP. strains against barley diseases caused by Bipolaris Sorokiniana on cultivars of different resistance

The effect of Bacillus strains, B. subtilis 16 and B. pumilus 11, on two barley diseases caused by Bipolaris sorokiniana (Sacc.) Shoemaker has been studied. It was found that the activity depends on both the resistance of the cultivar against disease and the bacterial strain. The severity of spot blotch of barley decreased significantly when the cell suspension of B. subtilis strain16 was sprayed on the leaves of disease-susceptible cultivars Nashсhadok, but failed to inhibit the disease on the leaves of resistant cultivars. Applying the cell suspensions into plant growth media significantly inhibited the common root rot on susceptible cultivar Syaivo, which, however, was not accompanied by an increase in the biomass of seedlings. A significant increase in the weight of shoots and roots of seedlings was observed on cultivars with medium resistance to the disease: Sebastian and Antey.

Synergistic Action of Commercially Available Fungicides for Protecting Wheat from Common Root Rot Caused by Bipolaris sorokiniana in China

Wheat (Triticum aestivum) common root rot (CRR) caused by predominant fungal pathogen Bipolaris sorokiniana occurs in all wheat-growing regions worldwide and is difficult to control. In this study, the efficacy of eight fungicides against Bipolaris sorokiniana was examined in in vitro assays, and we determined that the combined application of two fungicides significantly inhibits the growth of fungal mycelium. Half of the maximal effective concentration of a mixture containing fludioxonil and difenoconazole in the ratio 1:4 was 0.0372 mg/liter, and the cotoxicity coefficient was 160.14. Under an environmentally controlled pot assay, seed treatment with the mixture of fludioxonil and difenoconazole in the 1:4 ratio demonstrated the best control efficiency at seedling and adult stages, respectively. The best synergistic mixture on seed treatment was assessed in a 2-year field experiment at Hebei, China. The best control efficacy achieved at the seedling and adult stages was 82.65% and 68.48%, respectively. Overall, the in vitro mycelial growth inhibition assay and controlled-environment and field studies indicated that the synergistic action of a mixture of fludioxonil and difenoconazole provides effective control against wheat CRR. These findings highlight the potential application of the fungicide combination for controlling CRR and reducing the selection pressure on fungal pathogens by lessening the use of various fungicides in the field.