The cotton charcoal rot causal agent, Macrophomina phaseolina, biological and chemical control

Ofir Degani; Asaf Gordani; Elhanan Dimant; Assaf Chen; Onn Rabinovitz

doi:10.3389/fpls.2023.1272335

The cotton charcoal rot causal agent, Macrophomina phaseolina, biological and chemical control

Front Plant Sci. 2023 Sep 19:14:1272335. doi: 10.3389/fpls.2023.1272335. eCollection 2023.

Authors

Ofir Degani^{1

2}, Asaf Gordani^{1

2}, Elhanan Dimant¹, Assaf Chen^{2

3}, Onn Rabinovitz¹

Affiliations

¹ Plants Sciences Department, Migal-Galilee Research Institute, Kiryat Shmona, Israel.
² Faculty of Sciences, Tel-Hai College, Upper Galilee, Tel-Hai, Israel.
³ Soil, Water and Environment Department, Migal-Galilee Research Institute, Kiryat Shmona, Israel.

Abstract

The fungus Macrophomina phaseolina causes charcoal rot disease (CRD) in cotton, whose symptoms develop in the late stages of growth and result in wilting and death. Despite significant research efforts to reduce disease incidences, effective control strategies against M. phaseolina are an ongoing scientific effort. Today's CRD control tends toward green options to reduce the chemicals' environmental footprint and health risks. Here, different Trichoderma species were examined separately and in combination with Azoxystrobin (AS) in semi-field open-enclosure pots and a commercial field throughout a full season. In the pot experiment, the T. asperellum (P1) excelled and led to improvement in growth (13%-14%, day 69) and crops (the number of capsules by 36% and their weight by 78%, day 173). The chemical treatment alone at a low dose had no significant impact. Still, adding AS improved the effect of T. longibrachiatum (T7507) and impaired P1 efficiency. Real-time PCR monitoring of the pathogen DNA in the plants' roots at the harvest (day 176), revealed the efficiency of the combined treatments: T. longibrachiatum (T7407 and T7507) + AS. In a commercial field, seed dressing with a mixture of Trichoderma species (mix of P1, T7407, and Trichoderma sp. O.Y. 7107 isolate) and irrigation of their secreted metabolites during seeding resulted in the highest yields compared with the control. Applying only AS irrigation at a low dose (2,000 cc/ha), with the sowing, was the second best in promoting crops. The molecular M. phaseolina detection showed that the AS at a high dose (4,000 cc/ha) and the biological mix treatments were the most effective. Reducing the AS chemical treatment dosages by half impaired its effectiveness. Irrigation timing, also studied here, is proven vital. Early water opening during the late spring suppresses the disease outburst and damages. The results demonstrated the benefits of CRD bio-shielding and encouraged to explore the potential of a combined bio-chemo pest control approach. Such interphase can be environmentally friendly (reducing chemical substances), stabilize the biological treatment in changing environmental conditions, achieve high efficiency even in severe CRD cases, and reduce the development of fungicide resistance.

Keywords: Trichoderma; azoxystrobin; crop protection; field study; fungus; integrated control; irrigation; real-time PCR.

Grants and funding

The authors declare that this study received funding from The Israel Cotton Board Ltd. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication. The APC was funded by Migal—Galilee Research Institute.