2007 Controlling Liverworts During Nursery Production

Project: Controlling cryptogams during nursery production to improve Whitebark Pine seedling quality and reduce seedling costs.

Attachment: Controlling Liverworts PowerPoint

Agency/forest or park/ district: Coeur d’Alene nursery

Project coordinator: Kas Dumroese

Contact: Kas Dumroese – USDA Forest Service, Rocky Mountain Research Station, 1221 South Main, Moscow 83843.   208-883-2324   kdumroese@fs.fed.us


Kent Eggleston- USDA Forest Service, Coeur d’Alene Nursery

David Barcel- Chemtura Crop Protection

Anthony Davis- University of Idaho, Center for Nursery and Seedling Research

Source of funding /amount

FHP: $4,300

Supplemental funding: $4,000 from USDA FS Southern Research Station, $100 from Chemtura, $1,800 from U. of Idaho and $1,800 from USDA FS Coeur d’Alene Nursery

Dates of restoration efforts

Experiment conducted March 2007 through April 2007.


Control cryptogams (algae, moss, liverwort) during nursery production to enhance seedling quality, maximize seed-to-seedling ratios, and reduce propagation costs.

Acres/ha treated: N/A


Evaluated TerraCyte, a broad spectrum algaecide/fungicide labeled for use inside greenhouse, and Gentry, anew product currently being reviewed by the EPA for use on cryptogams in nurseries, at several application rates in first and second year crops of WBP seedlings growing in Ray Leach SC10 containers (Super Cells). A “tray” held 98 SC10 containers, and this was the experimental unit.

We had five treatments. The first four treatments included application of quinoclamine (Gentry; a fine powder; 26% 2-amino-3-chloro-1,4-naphthoquinone) mixed at a rate of 0.14, 0.28, 0.42, or 0.56 g in 100 ml of water and applied with a hand sprayer evenly across the tray. The 0.14-g rate was equivalent to manufacturers lowest suggested label rate (1 oz per gallon of water applied at 1 quart per 100 sq ft). The fifth treatment was application of TerraCyte (BioSafe Systems), a fine powder (34% sodium carbonate peroxyhydrate), applied at the label rate of 15 lb per 1000 sq ft (13.6 g per tray of seedlings) after wetting the crop to improve adherence of the chemical to plant tissue. We used a series of #30 and #40 standard soil sieves to ensure even distribution of the chemical across the block. The sixth treatment was a control: Application of 100 ml plain water with the hand sprayer.

Before applications, we also qualitatively rated the incidence of liverworts (low, medium, high).

Planting? If so, source of seedlings? Resistance?



The project was completed. Gentry effectively controlled liverworts and mosses growing in whitebark pine crops. When infestations of liverwort were low to moderate in nature (the liverworts covered <30% of the surface of the growing containers and were not yet reproductive), treating them with 0.14 g per 100 ml of water (equivalent to manufacturers lowest suggested label rate of 1 oz per gallon of water applied at 1 quart per 100 sq ft) killed liverworts in 24 to 48 hours. When infestations were high (liverworts formed a mat of vegetation 2 to 3 cm deep, covered about 90% of the surface of the container, and reproductive organs had formed), then a rate of 0.56 g Gentry per 100 ml (equivalent to manufacturer’s highest suggested label rate of 2 oz per gallon of water applied at 2 quarts per 100 sq ft) was required, and even at this rate, multiple applications were required to finally discourage the pest. Gentry was easy to mix and apply (much easier than TerraCyte, a product on the market and registered for liverwort control) and was not phytotoxic to whitebark pine seedlings, nor seedlings of ponderosa pine, Douglas-fir, western larch, kinnikinnick, willows, and wild ginger. TerraCyte had to applied as a powder and was difficult to apply evenly; the result was seedling mortality due to phytotoxicity. Seedlings were shipped to the outplanting site before final morphological assessment could be completed. Therefore, seedling quality is qualitative, rather than quantitative.

Monitoring since completion of the project

Will outcome meet goals?

This chemical would be effective and meet goals.

Future actions/follow up?

In 2007 the product was being reviewed by the US EPA and a decision was expected in January 2008. If approved, this work will provide foundation for treating the pest at the Coeur d’Alene Nursery with less labor. As of 2014, it does not appear that US EPA has approved this chemical for use in the US.

Miscellaneous comments

Results presented at the 2007 Intermountain Container Seedling Growers’ Association annual meeting in Moscow, Idaho.