Identification and characterization of Trichoderma species aggressive to Pleurotus in Italy
In the late 1980's the development of a severe epidemic of green mold caused by Trichoderma spp. was noted in the commercial production of Agaricus bisporus (champignon) in the United Kingdom, North America, Spain and Holland, which caused extensive economic losses. The parasitic fungi isolated...
Saved in:
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Zhejiang University Press
2004-07-01
|
| Series: | 浙江大学学报. 农业与生命科学版 |
| Subjects: | |
| Online Access: | https://www.academax.com/doi/10.3785/1008-9209.2004.04.0469 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | In the late 1980's the development of a severe epidemic of green mold caused by Trichoderma spp. was noted in the commercial production of Agaricus bisporus (champignon) in the United Kingdom, North America, Spain and Holland, which caused extensive economic losses. The parasitic fungi isolated from the edible mushroom belonged to four biotypes, Th1, Th2, Th3 and Th4 of T. harzianum. However, among these biotypes, only Th2 (since classified as T. aggressivum f. europaeum) and Th4 (T. aggressivum f. aggressivum) were identified as the fungi causing problems in Agaricus production. In general, mushroom compost hosts both aggressive and innocuous isolates of Trichoderma, which are not morphologically distinguishable. About four years ago, a problem with green mold became apparent in the production of Pleurotus ostreatus in Northern Italy, which eventually developed to a crisis situation in the South two years later and threatened to seriously compromise the Pleurotus market. This study was initiated to: isolate and identify the aggressive fungi, then morphologically, physiologically and genetically characterize the isolates, determine the source and phases of infection, and study methods of control. Samples were obtained from different phases of compost preparation at the locality of a major producer and supplier of compost to the mushroom industry in Southern Italy, and microbial counts were conducted. Although the presence of Trichoderma was detected in the initial stages of composting, this value was reduced to zero from the phase of pasteurization to seeding with Pleurotus. Trichoderma infestations were noted in the packaged Pleurotus bales at various times during the incubation phase (7-15 days after seeding) and after shipping to the mushroom greenhouses, where the pathogen infestations greatly reduced the quality and quantity of the mushroom yield, as well as the number of potential harvest cycles. Preliminary results from the morphological and genetic characterization of Trichoderma isolates parasitic to Pleurotus indicated that they are different from both T. aggressivum forms parasitic to Agaricus, and the majority of the isolates probably belong to the species T. harzianum. In vitro confrontation plates were performed with 26 isolates of aggressive Trichoderma obtained from compost, three Trichoderma isolates used in biological control and 12 varieties of Pleurotus. No inhibitory effect was observed between any of the Trichoderma isolates with Pleurotus, although some growth inhibition was caused by the biocontrol isolates of Trichoderma on some of the aggressive isolates. The temperature optimum for Pleurotus growth was at 28 ℃, whereas Trichoderma grew well at a wider range (20-28 ℃), and exceeded the growth rate of Pleurotus by three times at 25 ℃.The pH optimum for the growth of Pleurotus was alkaline (pH 8-9) whereas Trichoderma preferred acidic-neutral pH (5-7). Various commercial fungicides used in agriculture (procloraz, thiabendazole, dichloran, benomyl, propiconazole, thiofanatomethyl) were tested against the aggressive and biocontrol isolates of Trichoderma, as well as the different varieties of Pleurotus to determine dose response curves and combinations that would inhibit spore germination, mycelial growth and subsequent sporulation. Both procloraz and thiabendazole, which are pesticides allowed in edible mushroom production, were found to control the growth of the aggressive Trichoderma isolates and did not have a negative effect on Pleurotus. |
|---|---|
| ISSN: | 1008-9209 2097-5155 |