Environmental and irrigation conditions can mask the effect of Magnaporthiopsis maydis on growth and productivity of maize

Abstract

Maize production in temperate countries is threatened by late wilt, caused by Magnaporthiopsis maydis. Plant infection occurs early after sowing, but symptoms appear from flowering onwards. The disease is mainly controlled by genetic resistance, which is often partially expressed in the field. Development of disease symptoms is also highly dependent on environmental conditions. This study looked at whether production and growth of susceptible maize are affected by M. maydis under environmental conditions that are suboptimal for disease development. In addition, the effect of water availability on disease development under optimal conditions was determined. Pot experiments were conducted in an open‐air enclosure in 2013, 2015 and 2016. Under unfavourable conditions for disease (low air temperature and relatively high air humidity), aboveground symptoms did not appear in the plants despite growth and production variables being clearly altered by the fungus. When air temperatures and humidity were optimal for disease development (air temperatures relatively high and humidity rather low), leaf symptoms on inoculated plants became apparent but with secondary importance compared to decreases in growth and production. The pathogen also affected the root:aboveground biomass ratio to a greater extent when the plants were under good water conditions than under deficit irrigation. Under optimal conditions and with good soil water content, the infected crop may end its cycle without symptoms, with the disease undetected, although reductions in yield and aboveground biomass can occur.

Interactions between Magnaporthiopsis maydis and Macrophomina phaseolina, the Causes of Wilt Diseases in Maize and Cotton

“…It has now become evident that optimal water supply can reduce late wilt disease in maize. Indeed, our past experience [6,30,33] and a review of the literature support the conclusion that high water potential is one of the most important agrotechnical aims for restricting late wilt disease progression [17,[47][48][49]. The results presented in the current study are in line with this conclusion, with nearly 10 times higher M. maydis DNA in drought-stressed maize sprouts (37 DAS, Figure 2).…”

Trichoderma Biological Control to Protect Sensitive Maize Hybrids against Late Wilt Disease in the Field

“…The majority of those works focused on environmentally friendly substitutions to the traditional chemical fungicides. Briefly, these green approaches include: the effect of a tillage system and cover crop on maize mycorrhization and LWD [ 27 ]; siderophore production by Bacillus subtilis and Pseudomonas koreensis [ 34 ]; antagonistic other phytopathogens such as Macrophomina phaseolina [ 8 ]; agro-mechanical approaches such as excessive watering [ 54 ]; applying Lycium europaeum extracts [ 24 ]; manipulating maize plant’s growth hormones [ 55 ]; manipulating the root colonization by rhizobacteria; yeast and using organic compounds [ 56 , 57 ]; seed treatments with biocontrol formulations ( B. subtilis , B. pumilus , Pseudomonas fluorescens , and Epicoccum nigrum ); and bentocide, zinc oxide nanoparticles, and nano-silica [ 58 ]. As in other fungal pathogens, Trichoderma species have received particular focus in the research [ 22 ].…”

Trichoderma longibrachiatum and Trichoderma asperellum Confer Growth Promotion and Protection against Late Wilt Disease in the Field

“…The growing season (autumn) during which the second field experiment was conducted was less optimal for LWD development due to the drop in temperature and rain (Table 2), a known factor in reducing LWD [41]. Furthermore, we had deliberately infected the experimental field for the second year in a row.…”