Fungal species associated with crown and root rot diseases in wheat have been extensively studied in many parts of the world. However, no reports on the relative importance and distribution of pathogens associated with wheat crown and root rot in Kyrgyzstan have been published. Hence, fungal species associated with wheat crown/root rot were surveyed in three main wheat production regions in northern Kyrgyzstan. Fungal species were isolated on 1/5 strength potato-dextrose agar amended with streptomycin (0.1 g/L) and chloramphenicol (0.05 g/L). A total of 598 fungal isolates from symptomatic tissues were identified using morphological features of the cultures and conidia, as well as sequence analysis of the nuclear ribosomal internal transcribed spacer (ITS) region, the translation elongation factor 1α (TEF1), and the RNA polymerase II beta subunit (RPB2) genes. The percentage of fields from which each fungus was isolated and their relative percentage isolation levels were determined. Bipolaris sorokiniana, the causal agent of common root rot, was the most prevalent pathogenic species isolated, being isolated from 86.67% of the fields surveyed at a frequency of isolation of 40.64%. Fusarium spp. accounted for 53.01% of all isolates and consisted of 12 different species. The most common Fusarium species identified was Fusarium acuminatum, which was isolated from 70% of the sites surveyed with an isolation frequency of 21.57%, followed by Fusarium culmorum, Fusarium nygamai, Fusarium oxysporum, and Fusarium equiseti, all of which had a field incidence of more than 23%. Inoculation tests with 44 isolates representing 17 species on the susceptible Triticum aestivum cv. Seri 82 revealed that Fusarium pseudograminearum and F. culmorum isolates were equally the most virulent pathogens. The widespread distribution of moderately virulent B. sorokiniana appears to be a serious threat to wheat culture, limiting yield and quality. With the exception of F. culmorum, the remaining Fusarium species did not pose a significant threat to wheat production in the surveyed areas because common species, such as F. acuminatum, F. nygamai, F. oxysporum, and F. equiseti, were non-pathogenic but infrequent species, such as Fusarium redolens, Fusarium algeriense, and F. pseudograminearum, were highly or moderately virulent. Curvularia inaequalis, which was found in three different fields, was mildly virulent. The remaining Fusarium species, Fusarium solani, Fusarium proliferatum, Fusarium burgessii, and Fusarium tricinctum, as well as Microdochium bolleyi, Microdochium nivale, and Macrophomina phaseolina, were non-pathogenic and considered to be secondary colonizers. The implications of these findings are discussed.

A total of 434 isolates of Rhizoctonia belonging to 10 anastomosis groups were obtained from the roots and rhizosphere soils of bean and soybean plants grown in Samsun, Turkey. AG-4 was found to be the most common group on bean and soybean plants and AG-5, AG-6, binucleate AG-A, AG-B and R. zeae were other groups isolated from the both plant species. AG-1, AG-7 and AG-K from bean and AG-E from soybean were other groups obtained in the study. The pathogenicity tests on bean and soybean seedlings showed that the highest disease severities were caused by AG-4 isolates, whereas AG-1 and AG-6 isolates were moderately pathogenic. Binucleate Rhizoctonia AG-B isolates were also moderately pathogenic, while other binucleate Rhizoctonia were found to be weakly pathogenic. Rhizoctonia zeae isolates caused moderate disease symptoms on bean, but soybean plants were slightly affected by this group of isolates. This is the first reported observation of R. solani AG-6 and AG-7 and binucleate Rhizoctonia AG-B on bean, and R. solani AG-5 and AG-6 and binucleate Rhizoctonia AG-A, AG-B and AG-E on soybean, in Turkey.

A total of 132 Rhizoctonia isolates were recovered from red cabbage plants with root rot and wirestem symptoms in the province of Samsun (Turkey) between 2018 and 2019. Based on the sequence analysis of the internal transcribed spacer (ITS) region located between the 18S and 28S ribosomal RNA genes and including nuclear staining, these 124 isolates were assigned to multinucleate Rhizoctonia solani, and eight were binucleate Rhizoctonia. The most prevalent anastomosis group (AG) was AG 4 (84%), which was subdivided into AG 4 HG-I (81%) and AG 4 HG-III (3%), followed by AG 5 (10%) and AG-A (6%), respectively. The unweighted pair group method phylogenetic tree resulting from the data of 68 isolates with the inter-PBS amplification DNA profiling method based on interspersed retrotransposon element sequences confirmed the differentiation of AGs with a higher resolution. In the greenhouse experiment with representative isolates (n = 24) from AGs on red cabbage (cv. Rondale), the disease severity index was between 3.33 and 4.0 for multinucleate AG isolates and ranged from 2.5 to 3.17 for AG-A isolates. In the pathogenicity assay of six red cabbage cultivars, one isolate for each AG was tested using a similar method, and all cultivars were susceptible to AG 4 HG-I and AG 4 HG-III isolates. Redriver and Remale were moderately susceptible, while Rescue, Travero, Integro, and Rondale were susceptible to the AG 5 isolate. The results indicate that the most prevalent and aggressive AGs of Rhizoctonia are devastating pathogens to red cabbage, which means that rotation with nonhost-crops for these AGs may be the most effective control strategy. This is the first comprehensive study of Rhizoctonia isolates in red cabbage using a molecular approach to assess genetic diversity using iPBS-amplified DNA profiling.

The efficacy of the native entomopathogenic fungus, Isaria fumosorosea TR-78-3, was evaluated against females of the bark and ambrosia beetles, Anisandrus dispar Fabricius and Xylosandrus germanus Blandford (Coleoptera: Curculionidae: Scolytinae), under laboratory conditions by two different methods as direct and indirect treatments. In the first method, conidial suspensions (1 × 10⁶ and 1 × 10⁸ conidia ml⁻¹) of the fungus were directly applied to the beetles in Petri dishes (2 ml per dish), using a Potter spray tower. In the second method, the same conidial suspensions were applied on a sterile hazelnut branch placed in the Petri dishes. The LT₅₀ and LT₉₀ values of 1 × 10⁸ conidia ml⁻¹ were 4.78 and 5.94/days, for A. dispar in the direct application method, while they were 4.76 and 6.49/days in the branch application method. Similarly, LT₅₀ and LT₉₀ values of 1 × 10⁸ conidia ml⁻¹ for X. germanus were 4.18 and 5.62/days, and 5.11 and 7.89/days, for the direct and branch application methods, respectively. The efficiency of 1 × 10⁶ conidia ml⁻¹ was lower than that of 1 × 10⁸ against the beetles in both application methods. This study indicates that I. fumosorosea TR-78-3 had a significant potential as a biological control agent against A. dispar and X. germanus. Further studies are necessary to evaluate the efficacy of the isolate on the pests under field conditions.