Effective chemical protection against the maize late wilt causal agent, Harpophora maydis, in the field

PLoS One. 2018 Dec 18;13(12):e0208353. doi: 10.1371/journal.pone.0208353. eCollection 2018.

Abstract

Late wilt, a disease severely affecting maize fields throughout Israel, is characterized by relatively rapid wilting of maize plants before tasseling and until shortly before maturity. The disease's causal agent is the fungus Harpophora maydis, a soil-borne and seed-borne pathogen, which is currently controlled using reduced sensitivity maize cultivars. In a former study, we showed that Azoxystrobin (AS) injected into a drip irrigation line assigned for each row can suppress H. maydis in the field and that AS seed coating can provide an additional layer of protection. In the present study, we examine a more cost-effective protective treatment using this fungicide with Difenoconazole mixture (AS+DC), or Fluazinam, or Fluopyram and Trifloxystrobin mixture, or Prothioconazole and Tebuconazole mixture in combined treatment of seed coating and a drip irrigation line for two coupling rows. A recently developed Real-Time PCR method revealed that protecting the plants using AS+DC seed coating alone managed to delay pathogen DNA spread in the maize tissues, in the early stages of the growth season (up to the age of 50 days from sowing), but was less effective in protecting the crops later. AS+DC seed coating combined with drip irrigation using AS+DC was the most successful treatment, and in the double-row cultivation, it reduced fungal DNA in the host tissues to near zero levels. This treatment minimized the development of wilt symptoms by 41% and recovered cob yield by a factor of 1.6 (to the level common in healthy fields). Moreover, the yield classified as A class (cob weight of more than 250 g) increased from 58% to 75% in this treatment. This successful treatment against H. maydis in Israel can now be applied in vast areas to protect sensitive maize cultivars against maize late wilt disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / pharmacology
  • Antifungal Agents / pharmacology*
  • Ascomycota / drug effects*
  • Ascomycota / pathogenicity*
  • Benzamides / pharmacology
  • Dioxolanes / pharmacology
  • Imines / pharmacology
  • Plant Diseases / microbiology
  • Plant Diseases / prevention & control
  • Pyridines / pharmacology
  • Strobilurins / pharmacology
  • Triazoles / pharmacology
  • Zea mays / microbiology*

Substances

  • Acetates
  • Antifungal Agents
  • Benzamides
  • Dioxolanes
  • Imines
  • Pyridines
  • Strobilurins
  • Triazoles
  • prothioconazole
  • tebuconazole
  • difenoconazole
  • N-(2-(3-chloro-5-(trifluoromethyl)-2-pyridyl)ethyl)-alpha,alpha,alpha-trifluoro-o-toluamide
  • trifloxystrobin

Grants and funding

This work was supported by a research grant from the Israel Ministry of Agriculture and Rural Development, the Chief Scientist and a research grant number 21-35-0003, and from the Israel Northern R&D, MIGAL – Galilee Research Institute, Kiryat Shmona, Israel.