Biocontrol agents efficiently inhibit sporulation of Botrytis aclada on necrotic leaf tips but spread to adjacent living tissue is not prevented

Abstract

Ulocladium atrum (isolates 385 and 302) consistently inhibited Botrytis aclada sporulation on dead onion leaf pieces under constant moist conditions and with an interrupted wetness period of 9 h. Clonostachys rosea (isolate 201) was as effective as U. atrum under constant moist conditions, but was ineffective if exposed to a drying period. No sporulation of B. aclada was observed 8 and 12 days after inoculation in the presence of U. atrum 302. C. rosea 201 significantly reduced B. aclada sporulation 8 days, but not 12 days after inoculation. When U. atrum 302 or C. rosea 201 was applied 1 day prior to B. aclada the antagonistic effect was higher compared to when the antagonists were applied on the same day. C. rosea 201 and U. atrum 302 did not obstruct the growth of B. aclada from necrotic onion leaf tips into living tissue, when artificially induced necrotic leaf tips were infested with B. aclada 24 h prior to antagonists. Three days after antagonist application, no symptoms could be observed on the healthy leaf tissue, nor was there sporulation on the necrotic leaf tip. However, B. aclada was immunologically detected 2 cm below the inoculation site. We conclude that under constant moist conditions the antagonists C. rosea 201 and U. atrum 302 cannot stop the progress of B. aclada from necrotic into fresh leaf tissue.

Non-Chemical Methods for Controlling Seedborne Fungi in Carrot with Special Reference to Alternaria Radicina

“…The efficacy of C. rosea against different pathogens was proven earlier (Jensen et al 2000;Krauss and Soberanis 2001;Morandi et al 2003;Jensen et al 2004;Yohalem et al 2004;Nobre et al 2005). These reports found a confirmation in the presented experiment.…”

“…and A. alternata from rose (Rosa hybrida L.) interacted with C. rosea and reduced control of the pathogen by 16% and 21%, respectively (Morandi et al 2000). The study of Yohalem et al (2004) showed that C. rosea suppressed sporulation of B. aclada with variable efficacy. C. rosea was effective in suppressing B. aclada sporulation under constant moist conditions, but it was less effective if exposed to a drying period.…”

Spatiotemporal variation in the fungal community associated with wheat leaves showing symptoms similar to stagonospora nodorum blotch

“…The fungi T. harzianum and T. koningii decrease the impact of P. tritici-repentis and M. graminicola when applied to seeds and leaves (Perelló et al 2006). Ulocladium atrum and Clonostachys rosea prevent sporulation of Botrytis aclada (Yohalem et al 2004). The mechanism of antagonism is thought to be competition for the nutrients on the leaf surface (Fokkema et al, 1979).…”

Interaction of Ulocladium atrum, a Potential Biological Control Agent, with Botrytis cinerea and Grapevine Plantlets

“…This is in agreement with Köhl et al [10,11] who demonstrated very effective suppression of sporulation of B. aclada in dead onion tissue in bioassays and in onion plants. Also, Yohalem et al [4] have reported that, while U. atrum 302 efficiently inhibits sporulation of B. aclada on moribund leaf tips, latent infection or adjacent tissues was not prevented. Also, Szandala and Backhouse [12] found that antagonists such as Trichoderma harzanium reduce sporulation of B. cinerea in bean leaf assays when antagonists were applied 120 h after infection by the pathogen.…”

“…However, commercial applications of these antagonists have been limited so far. Fungi positioned in the genus Ulocladium are soil saprophytes and some species, including U. atrum and U. oudemansii, have potential for use in biocontrol against foliar diseases, such as those caused by the plant pathogenic genera Sclerotina and Botrytis [4,5]. For instance, U. oudemansii (isolate HRU3) was successfully commercialized and is the active ingredient in BOTRY-Zen ® , a BCA product that is approved for early-season Botrytis suppression in organic and conventional viticulture in New Zealand [6].…”