Pyricularia setariae: a potential bioherbicide agent for control of green foxtail (Setaria viridis)

Abstract

One hundred and thirty-three fungal isolates, pathogenic to green foxtail, were evaluated for weed control potential under controlled conditions. To determine weed control efficacy, these pathogens were applied as spore or mycelial suspensions at approximately 105propagules ml−1to green foxtail at the three-leaf stage. One week after inoculation, most isolates caused only minor injury to the plants, but 15 isolates caused 50 to 100% disease. Among the most efficacious isolates, only those ofPyricularia setariaeexhibited strong host specificity to the target weed, revealing no significant pathogenicity on 28 other plant species tested, including many important crops such as wheat, barley, and oat. On green foxtail leaves, conidia of this fungus germinated readily at 14, 20, and 26 C, but the process of germination and appressorial formation was more rapid at the higher temperatures. The fungus applied at the concentration of 105spores ml−1reduced weed fresh weight by 34% 7 d after the treatment when compared with controls, whereas a concentration of 107spores ml−1reduced fresh weight by 87%. This efficacy was comparable with that of the herbicide sethoxydim. When applied to the weed at the one- to four-leaf stages, the fungus reduced green foxtail fresh weight by more than 80%. Efficacy was slightly lower on plants at the five-leaf stage or older. On the green foxtail biotype resistant to the herbicide sethoxydim,P. setariaecaused 80% fresh weight reduction compared with untreated controls, as opposed to 17% achieved with the herbicide. At 20 C, the fungus required a minimum of 6-h dew period to initiate infection, but a 10-h dew period was needed to cause severe damage to green foxtail.

Interaction of a bioherbicide and glyphosate for controlling hemp sesbania in glyphosate‐resistant soybean

“…Recently, several herbicides, including glyphosate, were tested at reduced rates for possible interactions with the fungal pathogen, Pyriculoria setariae Niskoda, for the control of green foxtail ( Setoria viridis [L.] Beauv.) (Peng & Byer 2005). Propanil ( N‐ [3,4‐dichlorophenyl] propanamide), quinclorac (3,7‐dichloro‐8‐quinolinecarboxylic acid), and sethoxydim {2‐(1‐[ethoxyimino]butyl)‐5‐(2‐[ethylthio]propyl)‐3‐hydroxy‐2‐cyclohexen‐1‐one} applied 6 h prior to the pathogen generally resulted in greater efficacy.…”

Transcriptome analysis identified the mechanism of synergy between sethoxydim herbicide and a mycoherbicide on green foxtail

“…An isolate of P. setariae 94-409A, highly virulent to both HS- and HR-GFT biotypes 21 , was used throughout the study. Conidia (spores) were produced on oatmeal agar at 26 °C with a 14-h photoperiod under near-ultra violet light.…”

“…In a previous study, a host-specific fungal pathogen, Pyricularia setariae Nisikado, was efficacious against GFT seedlings, including the resistant biotype 7 . Applying sethoxydim at sub-lethal doses prior to or with P. setariae substantially improved its efficacy against GFT, extending the efficacy to older GFT plants and additional weedy foxtail species 8 .…”

Interaction of Glufosinate and <i>Colletotrichum truncatum</i> on Ammonia Levels and Glutamine Synthetase Activity in Hemp Sesbania

“…Glyphosate and the bioherbicide, Alternaria cassiae applied to sicklepod resulted in a synergistc interaction [34]. Synergy of two bacterial plant pathogens with glufosinate was also demonstrated in greenhouse and field studies [29], but results of synergy studies of glufosinate and Pyricularia setariae [bioherbicide for green foxtail (Setaria virdis)] were variable [35]. Furthermore, some commercial glyphosate products are toxic to certain bioherbicides.…”