Commercial Mushroom Farms Research Articles

Compost Filling Methods Affect Green Mold Disease Incidence in Commercial Mushrooms.

Green mold (Trichoderma aggressivum) is an invasive disease of commercial mushrooms introduced into the United States from Europe that now has spread to commercial mushrooms throughout North America. We examined potential sources of invasive green mold inoculum and the association with different compost filling technologies on a large actively producing commercial mushroom farm. Green mold foci were sampled bed by bed, which generated 20,906 data points. Logistic regression was used to determine treatment differences. Mechanical filling of compost into the beds reduced green mold incidence over hand filling, apparently due to the reduced incidence of worker contact with the floor and between beds. Lower growing beds located closer to the floor had a higher incidence of green mold for both mechanical and hand-filled beds. We conclude that mechanical filling and generally reducing contact with the floor and between beds will reduce spread of green mold in commercial mushroom production.

The Association Between Mushroom Sciarid Flies, Cultural Techniques, and Green Mold Disease Incidence on Commercial Mushroom Farms.

Many growers on mushroom farms producing white and brown varieties of Agaricus bisporus have noticed a potential association between sciarid fly (Lycoriella ingenua) pest populations and green mold (Trichoderma aggressivum) disease expression, and suspect that in addition to other preventative measures, controlling flies may be important to controlling green mold spread. In this study, we examined the association between L. ingenua populations and green mold disease incidence in commercial mushroom farms. In addition, we studied how relevant variables related to farming practices and farm characteristics may affect fly and disease incidence. Our data show that L. ingenua and green mold incidence are associated and that preventative measures such as sanitation and new technologies to reduce human-substrate contact are correlated with reduced green mold incidence. In addition, data indicated farm characteristics such as the proximity to neighboring farms as well as an organic mushroom growing regime are associated with fly incidence.

Agronomical valuation of a drip irrigation system in a commercial mushroom farm

Optimal mushroom growth is dependent on continuous water supply. Usually water is occasionally added by spraying on the casing layer. Drip irrigation system was developed in order to keep the optimal water contents in compost and casing during entire crop cycle. In this study, the use of drip irrigation system was compared to spray watering. The system (Netafim & Migal) is based on a unique dripper – Uniraam CNL 0.7 L/h that enables a very accurate and uniform water distribution in the substrates. Drip irrigation system led to more productive water use: yield of mushrooms was found to be higher (29.5 kg m−2 vs 27.6 kg m-2 for drip and spraying system, respectively) and higher mushroom quality was also found, with a higher percentage of “categorie I” mushrooms, that reduced picking costs. All of that helps to improve profitability of the mushroom crop.

Activity and distribution of the mushroom phorid fly, Megaselia halterata, in and around commercial mushroom farms

AbstractThe mushroom phorid fly, Megaselia halterata (Wood) (Diptera: Phoridae), is a key pest in mushroom farming in most parts of the world. Studies on the mushroom phorid fly have focused on its life history within mushroom growing houses, but little is known about the fly's activity outside mushroom growing houses. In this study, daily activity and distribution of adult M. halterata in the areas surrounding mushroom growing houses was studied using yellow sticky traps. Results suggest that M. halterata focuses its flight activity over turf areas rather than windbreaks and spent compost piles, possibly for mating purposes. Our study found no evidence of M. halterata breeding in turf areas surrounding mushroom growing houses. In addition, flight activity is highest in the afternoon until midnight at higher temperatures, yet at lower temperatures activity ceases after sunset. Establishing temperature and daylight thresholds for M. halterata flight activity may be useful in developing integrated pest management (IPM) tactics for this species. The most successful IPM tool that mushroom growers use at present is fly exclusion. Exclusion can be improved by focusing farm operations around temperature and daylight thresholds when fly activity is at its lowest.

Phoretic relationship between the myceliophagous mite Microdispus lambi (Acari: Microdispidae) and mushroom flies in Spanish crops

We studied the role played by the phorid Megaselia halterata (Wood) and the sciarid Lycoriella auripila (Winnertz) in the phoretic dispersion of the myceliophagous mite Microdispus lambi (Acari: Pygmephoridae). Twenty‐four crops were monitored during 18 months in commercial mushroom farms in Castilla‐La Mancha (Spain). Adults of both species were collected weekly and the mites they carried were counted and identified. Both phorids (19.6%) and sciarids (4.4%) carried the mite M. lambi. The calculated load of each was 3.4 M. lambi mites per phorid and 1.9 per sciarid. The same percentage of male and female phorid was used as vector, but the load was slightly higher for females (1.86 mites per female compared with1.48 mites per male). A mean of 7.2% of the phorids examined in winter were vectors of M. lambi, while in spring and autumn of the first year the average was more than 22%. The mean load did not vary significantly between seasons. Inside the mushroom farms, less than 10% of a small initial population of phorids carried mites (less than two mites per phorid). As the cycle progressed, more than 35% of a larger population of emerging flies did so (average 3.5 mites per phorid vector). At the end of the growth cycle, the flies may fly off to colonise nearby farms, favouring the propagation of M. lambi from infested to uninfested crops. Megaselia halterata is the principal vector of M. lambi in the mushroom farms of Castilla‐La Mancha due to their high numbers, the high percentage carrying mites and the number of M. lambi they carry.

Biological control of the fungus gnats Bradysia difformis (Diptera, Mycetophilidae) in mushrooms with Heterorhabditis amazonensis in tropical conditions

Sciarids from the genus Bradysia have gained attention due to their damaging presence in many protected crops in both temperate and tropical environments. In Venezuela, these flies called “fungus gnat” have turned into a hard pest to control in mushroom facilities, due to restrictions on the usage of chemical product after setting the casing layer and during the fructification period. For these reasons, we evaluated the use of native entomopathogenic nematodes as biological control agents to control Bradysia difformis in both laboratory and field conditions. Different Venezuelan nematode species or isolates were tested using fungus gnat larvae in laboratory condition, of which Heterorhabditis amazonensis (LPV-498) was the best performer at low temperatures. The nematodes were then tested in commercial mushroom farms using different dosses and application times. In the present work, H. amazonensis demonstrated that bags treated with nematodes, produced more mushrooms per bag than those treated with the normal chemical protocols. The highest production was reached when 3 million nematodes were applied after setting the casing layer, with 3766±1004g of harvested mushrooms per bag, an 44% increase of mushroom yield of compared with bags treated only with chemical products.

Pest Management on Us Commercial Mushroom Farms

Pest Management on Us Commercial Mushroom Farms

First Report of Syzygites megalocarpus (Mucorales) Web Mold on the Commercial Portabella Button Mushroom Agaricus bisporus in North America.

Agaricus bisporus (Lange) Imbach mushrooms, which are cultivated commercially under environmentally controlled conditions, are the most valuable crop in Pennsylvania. In August 2011, we first observed a mucoraceous mold colonizing primordia and mature basidiocarps of a new brown portabella strain of A. bisporus at two commercial mushroom farms in Chester County, PA. This strain is a hybrid between a commercial strain producing white basidiocarps and a brown wild type isolate of A. bisporus. Mushrooms mature in weekly "flushes". By third flush, 25% of the production surface at both farms was colonized by a fast growing mycelium that was initially white, subsequently yellow to golden brown, and finally grayish. Mushrooms colonized by the mold showed pitting, discoloration, and necrosis. Two pure cultures of the mold were obtained by the hyphal tip method from mature, necrotic basidiocarps at each farm. These isolates were accessioned in the ARS Culture Collection (NRRL, Peoria, IL) as NRRL 54814 to 54815 and 54818 to 54819. The cultures produced abundant aerial sporangiophores that branched dichotomously on potato dextrose agar. Light microscopic examination revealed that each branch terminated in a globose, multispored sporangium with a conspicuous columella. Individual cultures of NRRL 54818 and 54819 produced large (175 to 250 × 200 to 250 μm), barrel-shaped, dark brown to black zygosporangia between opposed suspensors, indicating they were homothallic. Morphological and cultural characteristics of the mold matched the description of Syzygites megalocarpus (3), a member of the Mucorales reported to colonize diverse, mostly fleshy basidiomycetes (2), including cultivated matsutake (Tricholoma matsutake) in Korea (1). Molecular phylogenetic confirmation of the morphological identification was obtained by PCR amplifying and sequencing domains D1 and D2 at the 5' end of the nuclear ribosomal large subunit (LSU rDNA). The four isolates shared an identical LSU rDNA allele. A search of the NCBI nucleotide database, using a partial LSU rDNA sequence from NRRL 54814 as the BLAST query, revealed that it shared 99.5% identity with AF157216.1, a reference isolate of S. megalocarpus NRRL 6288 (3). To assess whether cultures of S. megalocarpus could induce the disease, caps of portabella and white button mushrooms were inoculated with 3.7 × 106 sporangiospores. When incubated in moist chambers at 21 to 22°C with a 12-h photoperiod, disease symptoms developed in 2 to 3 days on portabella that included discoloration and pitting at the site of inoculation. S. megalocarpus was reisolated from the symptomatic mushrooms and produced a colony identical to the original. By comparison, white button mushrooms inoculated with S. megalocarpus, using the same method, only showed minor pitting and discoloration. Disease symptoms were not observed on mushrooms inoculated with water as a negative control. Although development of new commercial varieties derived using "wild" genetically diverse stocks is an effective way to introduce desirable traits into cultivated mushrooms, it carries the risk of introducing new diseases into the industry.

Analysis of Fresh Mushroom Compost

Fresh mushroom compost is a byproduct of the edible mushroom (Agaricus bisporus) industry and represents the composted growing substrate that remains after a crop has been harvested to completion. Thirty samples were obtained from commercial mushroom farms in southeastern Pennsylvania and sent to a laboratory for analysis to determine plant nutrient content, bulk density, and particle size distribution of fresh mushroom compost. Fresh mushroom compost had an average pH of 6.6, with an average carbon:nitrogen ratio of 13:1. Organic matter content averaged 25.86% (wet weight), 146.73 lb/yard3 (wet volume) or 60.97% (dry weight). For the primary macronutrients, average total nitrogen content averaged 1.12% (wet weight), 6.40 lb/yard3 (wet volume) or 2.65% (dry weight), phosphorus measured 0.29% (wet weight), 1.67 lb/yard3 (wet volume) or 0.69% (dry weight), and potassium was 1.04% (wet weight), 5.89 lb/yard3 (wet volume) or 2.44% (dry weight). Average soluble salt content was 13.30 mmho/cm (wet weight basis). However, on a per acre basis, the calculated sodium absorption ratio of 0.38 was considered very low. The average bulk density of fresh mushroom compost was 574.73 lb/yard3 (wet volume basis), and 91% of the material measured ≤3/8 inch in diameter as determined on a wet weight basis. Overall, fresh mushroom compost is suitable as a natural organic fertilizer and soil amendment for agriculture and horticulture.

First record of Hormiactis cap spot of mushrooms in Australia

Hormiactis cap spot of cultivated mushrooms is reported for the first time in Australia. Hormiactis alba was isolated from mushroom caps grown in a commercial mushroom farm in Central Victoria. A simple wound inoculation experiment showed that it grows rapidly on the caps of Agaricus bisporus.

Evaluation of a genetically selected strain of Steinernema feltiae against the mushroom sciarid Lycoriella mali

SUMMARYThe control potential of a strain (ScP) of Steinernema feltiae genetically selected against the mushroom sciarid Lycoriella solani, was evaluated for the management of L. mali. Trials were conducted at two commercial mushroom farms with high and low levels of fly infestation. The efficacy of the ScP strain was compared with the SN strain of S. feltiae and the chitin synthesis inhibitor, diflubenzuron. At low densities of L. mali, the two strains did not differ in efficacy and caused 85–94% reduction in fly populations. At high fly densities with a mixed infestation of the phorid fly, Megaselia halterata, the ScP stain caused 56–83% reduction in L. mali populations whereas the SN strain caused 51–73% reduction. Two doses of the improved strain (0.5 times 106 and 1.0 times 106 infective juveniles per m2 cropping area) did not differ in efficacy from diflubenzuron which caused 80% reduction in L. mali populations. The lower dose (0.5 times 106) of the SN strain was less effective than diflubenzuron. The ScP strain had a major advantage over the SN strain in persistence in casing material. Nematodes had no significant effect on mushroom yields.

Transmission of La France Isometric Virus During Basidiosporogenesis in Agaricus Bisporus

La France disease is a major limiting factor in the production of the cultivated mushroom Agaricus bisporus (Lange) Imbach. A viral etiology for this disease was first proposed in 1962, following the discovery of several types of viruslike particles (VLPs) in affected basidiocarps (11). Shortly thereafter, it was demonstrated that the causal agent could be transmitted to healthy mushroom crops via diseased mycelium (8, 20) and basidiospores (18, 20). Basidiospores are now considered the primary source of infection in the epidemiology of the disease, because of their typically high concentrations encountered at commercial mushroom farms. Levels of basidio-

Bendiocarb and diflubenzuron as substitute insecticides for endosulfan in commercial mushroom growing

SummaryDiflubenzuron and bendiocarb treatments of compost and casing soil at a rate of 1 g a.i./m2 each, resulted in comparable or even improved compost and casing soil colonisation over endosulfan treatments (at a rate of 1.5 g a.i./m2). Alternating diflubenzuron/bendiocarb treatments were preferable to the reverse treatments, which tended to diminish total yield of mushrooms significantly by 1.4–3.9 kg/m2. This effect was due to the casing soil treatment with diflubenzuron and not due to the compost treatment with bendiocarb after spawning. The effectiveness of these substitutes for endosulfan was tested on five commercial mushroom farms, where a similar or improved control of Megaselia halterata (Diptera: Phoridae) was obtained over control (endosulfan) treatments. If present, Lycoriella auripila (Diptera: Lycoriidae) was very effectively controlled by the substitute insecticides compared with endosulfan. Relatively high numbers of M. halterata were occasionally observed in endosulfan‐treated houses, indicating that a certain level of resistance towards this insecticide may already have developed. This assessment of tolerance in M. halterata emphasised the need for substitute insecticides with different modes of action, in addition to environmental reasons. The chemicals should be alternately applied within individual crops to avoid resistance development.

Sources of Verticillium fungicola on a commercial mushroom farm in England

From 1979 to 1981 Verticillium fungicola, a pathogen to Agaricus bisporus, was detected in 47 out of 485 samples of baled peat and in one out of 126 samples of bagged limestone arriving at an isolated mushroom farm in the UK. The pathogen was not detected in 875 samples of water, soil, mushroom spawn or spawned compost. Casing (a mixture of peat and limestone) prepared and used on the farm contained detectable V. fungicola in 25 out of 108 samples. The primary sources of V fungicola were thus the two constituents of casing, especially peat.Secondary sources of V. fungicola were numerous and included symptomless and diseased mushrooms, pickers and other staff, floors and doors and the principal pests (sciarid flies and mites).Viable airborne spores of V. fungicola were detected with an Andersen sampler in farm buildings at all stages in crop production. The spore load increased with the age of the crop. Few airborne spores were detected immediately outside affected buildings, and very few at the farm entrance 30 m away. There was no evidence that V. fungicola reached the farm from the surrounding air. despite substantial soil disturbance nearby.Selective media for V. fungicola are described.

Yellow Blotch of Pleurotus ostreatus

Yellow blotch disease of the oyster mushroom (Pleurotus ostreatus) was first observed in a commercial mushroom farm in California in 1983. The disease, caused by Pseudomonas agarici, is characterized by primordia, with yellow droplets on their surface, which become stunted, yellow to orange, and deformed as they mature.

Studies on the control of wet bubble disease of mushrooms with benzimidazoles

Wet bubble disease of the cultivated mushroom was controlled by incorporating benzimidazoles in the casing. Benomyl at the rate of 0.95 g/m2, and carbendazim and thiabendazole at the rate of 0.62 g/m2, were effective in controlling the disease. The benzimidazoles applied to casing were sufficient to give good control whether the inoculum was introduced before or after casing. A number of cases were observed in commercial mushroom farms where the disease was causing significant crop losses in spite of the use of benzimidazoles. This lack of control was found to be due to the unavailability of the applied fungicides following their absorption onto the casing. Exhaustive extraction methods yielded the greater part of the benzimidazoles applied to peat moss and spent compost casing materials. No bacterial degradation of the benzimidazoles applied to casing was observed.