Mushroom-Mushroom fly

Cecid flies (Mycophila speyeri, Heteropeza pygmaea)
House fly (Musca domestica)
Phorid fly (Megaselia halterata)
Sciarid fly (Lycoriella mali)
Stable fly (Stomoxys calcitrans)

Pest Biology and Crop Damage The major insect pest of mushrooms is the sciarid fly, a small black insect about 0.25 inch long, with long antennae and gray wings folded over the back. Sciarid larvae attack compost, spawn, mycelia, pins, and mushroom stems and caps. Phorid flies are small, 0.125 inch long, with a humpback appearance and very small antennae. They are stockier than sciarids and are very active, running and hopping erratically. These flies feed on mycelia, depressing crop yields. Both sciarid and phorid adults carry disease organisms into the crop. Cecid species are rarely seen as adult flies, because under the warmth of mushroom culture larvae become "mother larvae" giving birth directly to 10-30 daughter larvae. Cecids feed on the mushroom stems or gills, reducing marketable yield. Stable fly and house fly are common pests in compost wharves.

A detailed description of growing and pest management practices can be found in Pennsylvania Mushroom IPM Handbook (http://pubs.cas.psu.edu/FreePubs/pdfs/AGRS83.pdf).

Management-cultural control

Cultural control, including sanitation, composting and pasteurization is the basis for successful mushroom culture. Cultural practices that can reduce pest fly populations include exclusion, sanitation (washing and sanitizing), shortening crop cycles and post-harvest steam cleaning. In compost wharves, fly populations can be reduced by promoting drainage and reducing of standing. Fly exclusion is critical: rooms should be sealed and properly screened to exclude breeding flies. Attention should be paid to doors, fans, ceiling joints, drains and ductwork. Lights traps near doorways may be of value. Equipment and personnel should not move from older culture rooms (where infestations tend to exist) to newer, uninfested rooms. Limit the amount of time that doors are left open.

Management-biological control

Because of the moist organic growing media, a number of entomopathogenic nematodes are used successfully against mushroom flies. Steinernema feltiae is effective against sciarids. Howardula hussey occurs naturally in phorid populations. Bacillus thuringiensis israelensis (Bti) is a bacterium used widely in biocontrol of flies: Bti appears to be more effective against earlier instar sciarid larvae.

In compost wharves, augmentation of naturally occurring pteromalid wasps is used for control of house fly and stable fly: Spalangia endius, Muscidifurax raptor, M. zaraptor, and M. raptorellus are commercially available.

Management-chemical control

Note: Some labels specify Agaricus bisporus (the button mushroom) as the intended crop. In such cases, the product is registered legally for use only on Agaricus mushrooms.

Mushroom sites, pests, and controls

Site

Controls -follow label rates-

Comments and cautions

Empty mushroom house
and premises

azadirachtin (neem)

pyrethrin + PBO
permethrin (empty house only)

Filling

azadirachtin (neem)

Spawning

azadirachtin (neem)

Beauveria bassiana GHA

cyromazine1

To be effective, pesticides must be incorporated thoroughly into the compost. It is important that end sections and sides be treated completely.

Casing

azadirachtin (neem)

Beauveria bassiana GHA

Drench onto casing layer with sufficient water for good penetration.

Growth-Pinning

azadirachtin (neem)

malathion

pyrethrin + PBO
permethrin

Adult fly control.

Picking

pyrethrin + PBO (aerosol)

Use effectively to knock down adult flies prior to pickers entering rooms.

1Cyromazine-treated spent compost cannot be used to grow food crops.

Pesticides registered for use in mushroom houses and/or on mushroom crops

Common name

Brand names

Class1

Toxicity class

Uses and precautions

azadirachtin (neem)

Azatin, Align, Azasol, Debug Tres

BP

IV; very low

Sciarid and phorid fly control incorporated into compost or casing soil; disrupts fly development. Some formulations are OMRI-listed for organic use.

Beauveria bassiana GHA

Botanigard

MI

IV; very low

Sciarid and phorid fly control incorporated into compost or casing soil; fungus infects fly larvae. Some formulations are OMRI-listed for organic use.

cyromazine

Armor, Aegis

IGR

III; low

Sciarid fly control incorporated into compost; disrupts fly development. Spent, treated compost cannot be used to grow food crops.

malathion

Malathion

OP

lll; low

Sciarid and phorid flies, applied after picking.

permethrin

Ambush, Pounce

SP

II-III;
medium-low

Sciarid and phorid fly control as a fog, aerosol, or dust treatment for adult flies. Do not use when mushrooms are present.

piperonyl butoxide (PBO)

synergist

IV; very low

Improves activity of other ingredients; usually combined with pyrethrins.

pyrethrin, pyrethrum

many

NP

III; low

Aerosol or liquid; general insect control; very rapid knockdown. Some formulations are OMRI-listed for organic use.

1BP = biopesticide; IGR = insect growth regulator; MI = mycoinsecticide; NP = natural pyrethrum; OC = organochlorine; OP = organophosphate; SP = synthetic pyrethroid.

Note Some labels are labeled for use on Agaricus mushrooms only.