Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2015
Publication Date: 10/30/2015
Citation: Boyette, C.D., Hoagland, R.E., Stetina, K.C. 2015. Biological control of Spreading Dayflower (Commelina diffusa) with the fungal pathogen Phoma commelinicola. Agronomy Journal. 5:519-536.
Interpretive Summary: Spreading dayflower (Commelina diffusa) is a perennial, monocotyledenous weed distributed world-wide, and is highly invasive in several crops. It was one of the first plants with reported incidences of herbicide resistance (2,4-D). In greenhouse and field experiments we found that conidia of the fungus Phoma commelinicola exhibited bioherbicidal activity on spreading dayflower seedlings at temperatures of 25-30 °C, and a dew period of = 12. Maximum control (80%) and plant dry weight reduction (90%) required 21 h of dew. Mortality and dry weight reduction values in field experiments were 70% and 80%, respectively when cotyledonary-third leaf growth stage seedlings were sprayed with 108 or 109 conidia ml-1. These results indicate that P. commelinicola has potential as a biological control agent for controlling this problematic weed that is tolerant to several herbicides.
Technical Abstract: Greenhouse and field experiments showed that conidia of the fungal pathogen, Phoma commelinicola exhibited bioherbicidal activity on spreading dayflower (Commelina diffusa) seedlings when applied at concentrations of 106 to 109 conidia ml-1. Greenhouse tests determined an optimal temperature for conidial germination of 25-30 °C and that sporulation occurred on several solid growth media substrates (PDA, dayflower infusion agar). A dew period of = 12 h was required to achieve 60% control of cotyledonary-first leaf growth stage seedlings when applications of 108 conidia ml-1 were applied. Maximal control (80%) required longer dew periods (21 h) and 90 % plant dry weight reduction occurred at this dew period duration. More efficacious control occurred on younger plants (cotyledonary-first leaf growth stage) than older, larger plants. Mortality and dry weight reduction values in field experiments were ~70% and >80%, respectively when cotyledonary-third leaf growth stage seedlings were sprayed with 108 or 109 conidia ml-1. These results indicate that this fungus has potential as a biological control agent for controlling this problematic weed that is tolerant to the herbicide glyphosate.