Metarhizium brunneum strain F52
A soil fungus that infects and kills insects, not an insect you release. Strain F52 of Metarhizium brunneum (formerly M. anisopliae) is sold in the US as LALGUARD M52, previously Met52. The granules are mixed into potting media and soil against thrips pupae and black vine weevil larvae; the liquid is drenched or sprayed for thrips, whiteflies, mites and aphids. The spores stick to an insect, grow through its skin and kill it in 3–7 days at moderate temperatures. It lasts longest in soil and potting mix. It is not labelled for wireworms in the US, and field trials against them have been inconsistent.
At a glance
- Mode
- Fungal spores — infect on contact
- Granule rate
- 1.5–3 lb / cubic yard of soil or mix
- Drench rate
- 4–8 fl oz / 10 gal
- Speed
- Insects die 3–7 days after exposure
- REI / PHI
- Granules 12 h; liquid 4 h; PHI 0 days
- Storage
- Granules below 73 °F; liquid below 68 °F
How it works
Metarhizium is a fungus that lives naturally in soil and infects insects. Its spores attach to an insect's skin, germinate, and grow through the cuticle into the body. The label puts death at 3 to 7 days after exposure at moderate temperatures, and slower when it is very cold or hot. That temperature limit matters in soil. In a laboratory study of a wild Metarhizium isolate on the wireworm Agriotes obscurus, Kabaluk and Ericsson found significant disease and mortality at 18 °C (64 °F) but not at 6 or 12 °C (43 or 54 °F). The label says the spores persist longer in soil, and above all in potting media, than on leaves. The granule label adds that a spring incorporation, before egg-laying, lasted through two black vine weevil egg-laying seasons.
In greenhouse cages, three sprays of strain F52, 7 to 14 days apart, cut chilli thrips on pepper by 84–93%, close to spinosad (94–99%) and above the horticultural oils tested (58–85%) (Arthurs and colleagues, 2013). The residential use on lawns, against ticks, has a weaker record. In a randomised four-to-five-year trial across 24 New York neighbourhoods, Met52 had no significant effect on tick numbers, tick encounters or tick-borne disease (Ostfeld and colleagues, 2023). A separate study found it did not reduce non-target arthropods in lawns and woodland.
Applying it
The rate is set by the product label. The figures below come from the LALGUARD M52 GR (EPA Reg. 64137-31) and LALGUARD M52 OD (EPA Reg. 64137-33) labels, and Lallemand's OD technical sheet. Read the label on the product you buy: the residential sublabel of the OD covers ticks on lawns only. The soil, potting-mix, thrips and weevil uses are greenhouse, nursery and crop uses.
Granules: 1.5–3 lb per cubic yard
Or 25–50 g per cubic foot of soil or potting mix, mixed in thoroughly before or at planting. Use the higher rate when larval pressure is expected to be high.
Liquid: 4–8 fl oz per 10 gal
Water it into the top 2 inches of soil without runoff; for pots, about 8 oz of mix per gallon pot. Foliar sprays are 0.5–2.5 tsp per gallon.
Ahead of the pest
Apply before the target passes through the top 2–6 inches of soil. Soil applications repeat every 4–6 weeks (granules) or 2–6 weeks (liquid).
Cool and dry
Granules below 73 °F (23 °C); liquid below 68 °F (20 °C). The liquid keeps 12 months at ≤68 °F or 18 months at 39 °F; once opened, reseal it, keep it at 39 °F and use it within 3 weeks.
When to choose something else
Metarhizium works in soil and potting mix, slowly, and best when warm. Choose something else when:
- The pest is wireworms — it is not on the US label, and field results have been inconsistent; bait and rotate instead
- Soil is still cold — in lab work with a wild Metarhizium isolate, wireworms were not significantly infected at 54 °F (12 °C) or below
- You are treating garden beds rather than pots or a greenhouse — the thrips and weevil uses are greenhouse, nursery and crop uses, and the only home use on the labels is ticks on lawns; for soil pests in the garden, see Heterorhabditis bacteriophora and Steinernema feltiae
- The aim is fewer ticks in the yard — a large New York trial found no reduction in ticks or tick-borne disease
Where to buy
These are the registered products whose labels we checked. They are not ranked, and helpfulbugs takes no commission. Lallemand's technical sheet pitches the liquid at commercial greenhouse growers.
- LALGUARD M52 GR, formerly Met52 Granular (EPA Reg. 64137-31)2.2–25 lb bagsUS · GREENHOUSE & NURSERY
- LALGUARD M52 OD, formerly Met52 EC (EPA Reg. 64137-33)8 fl oz, 34 fl ozUS · AG; RESIDENTIAL LAWNS (TICKS)
Metarhizium brunneum strain F52 by target
Rate and timing differ by what you are releasing it against. Each page below is the program for one pest.