UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

 OFFICE OF CHEMICAL SAFETY 

 AND POLLUTION PREVENTION 

November 2, 2011 

MEMORANDUM 

SUBJECT: Environmental risk assessment for the FIFRA Section 3 registration of 

Phoma macrostoma strain 94-44B (PC Code 080303; EPA Reg. Nos. 239-

ETNE, 239-ETNG, 239-ENTU) for control of broadleaf weeds in turf and 

ornamentals 

FROM: Shannon Borges, Biologist /signed/

 Microbial Pesticides Branch 

 Biopesticides and Pollution Prevention Division, 7511P 

TO: Kathleen Martin, Regulatory Action Leader 

 Microbial Pesticides Branch 

 Biopesticides and Pollution Prevention Division, 7511P 

PEER REVIEW: Gail Tomimatsu, Ph.D., Plant Pathologist /signed/ 

 Microbial Pesticides Branch 

 Biopesticides and Pollution Prevention Division, 7511P 

The Scotts Company, LLC (hereafter “Scotts”), has submitted an application to register the 

microbial pesticide control agent (MPCA), Phoma macrostoma strain 94-44B, for control of preand post-emergent weeds in ornamentals and turf (including seed starting, field nursery, 

landscape, and container uses), and on impervious surfaces, such as patios, driveways, and 

sidewalks. Phoma macrostoma strain 94-44B is the active ingredient in the manufacturing use 

product, Phoma Tech (EPA Reg. No. 239-ENTE), and the end-use products, Phoma H (EPA 

Reg. No. 239-ENTG) and Phoma P (EPA Reg. No. 239-ENTU). Each of these products is 

composed of the same materials, and contains 92% Phoma macrostoma strain 94-44B at a 

minimum of 103

 CFU/g. Phoma H is to be marketed to homeowners and other nonprofessional 

applicators, while Phoma P is to be marketed to professional users. This memorandum contains 

BPPD’s environmental risk assessment for the proposed registration of Phoma macrostoma

strain 94-44B. 

A. Introduction 

Phoma macrostoma is a coelomycetous fungus that is commonly isolated from woody plants. It 

is also found incidentally on other plants (Boerema and Dorenbosch 1970, Boerema et al. 2004) 

and in soil and leaf litter (Bengtsson et al. 2005, Newsham 2003). It has been isolated from 
2

plants (mainly trees) in several states within the U.S. (Farr and Rossman 2011), and is found 

worldwide (Aveskamp et al. 2008). It has not been reported as a widely prevalent 

phytopathogen in the contiguous U.S. (UGA 2011). Several species in the Phoma genus are 

considered to be relevant phytopathogens (Aveskamp et al. 2008). While Phoma macrostoma is 

generally regarded as a weak pathogen or wound parasite (Caesar, et al., 2011, De Gruyter et al. 

2002, Boerema et al. 2004, see also Chauhan and Pandey 1991, Shattock and Askew 1980, 

Williamson and Hargreaves 1979), there are several reports of Phoma macrostoma causing 

primary disease in plants (e.g., Caesar, et al., 2011, Baird 1993, Jamaluddin 1977, Kubota and 

Abiko 2002, Sidhu and Singh 1979). Many species of Phoma exist as saprobes in the absence of 

suitable host plants, but will switch to a pathogenic existence when a suitable host plant is 

encountered (Aveskamp et al. 2008). A host list for Phoma macrostoma is available in Boerema 

and Dorenbosch (1970) and Farr and Rossman (2011), and the applicant has also provided a list 

of susceptible plants for P. macrostoma strain 94-44B, which is provided in Section C.1. 

Phoma macrostoma strain 94-44B was initially isolated from diseased Canada thistle (Cirsium 

arvense L.), and has been developed as a microbial pesticide for broadleaf weeds in turf and 

ornamentals. Effects on plants include chlorotic leaf spots, necrosis, and severe bleaching of 

emerging leaves. These effects can be lethal, although treated plants recover in some cases. The 

mode of herbicidal action is considered bimodal; fungal mycelia infect plant root systems and 

produce phytotoxic macrocidins, which cause foliar chlorosis and bleaching (Bailey, et al., 

2010). 

B. Summary of Nontarget Effects and Environmental Fate Studies 

Table 1 provides the status of the data requirements as published in 40 CFR § 158.2150 for the 

nontarget organism testing conducted on the active ingredient (TGAI), Phoma macrostoma strain 

94-44B. Studies were submitted to satisfy data requirements for avian oral 

toxicity/pathogenicity, freshwater fish and invertebrate toxicity/pathogenicity testing, nontarget 

insect testing, honey bee testing, and nontarget plant testing (terrestrial and aquatic). Scientific 

rationale was submitted to satisfy the data requirement for wild mammal toxicity/pathogenicity 

testing. Evaluation of the studies and scientific rationale submitted to support the registration of 

Phoma macrostoma strain 94-44B was completed by joint review with the Health Canada Pest 

Management Regulatory Agency. Relevant information from the open peer-reviewed literature, 

submitted studies and scientific rationale are included in environmental risk assessment. Data 

Evaluation Records (DERs) of the scientific rationale and studies are attached to this 

memorandum. 

The scientific evidence from peer-reviewed literature and the test data and information from 

submitted studies conducted by the applicant are sufficient to satisfy all Tier I nontarget 

organism data requirements and for nontarget organism risk assessment for the active ingredient 

(see Table 1). Additional data and information from published studies (e.g., Bailey et al. 2010, 

Bailey et al. 2011a, 2011b, Zhou et al. 2004) described the infection and colonization processes 

in plants and the environmental fate of Phoma macrostoma strain 94-44B. This information was 

determined sufficient to satisfy Tier II testing for the proposed uses, and are detailed below in 

Section C. 
3

The Agency also sought respective opinions from the USDA-APHIS-PPQ, and a plant 

pathologist at the Cornell University concerning the regulated status of Phoma macrostoma as a 

plant pathogen, and its ecological relevance as a plant pathogen, relative to other pathogenic 

species of Phoma.

Table 1. Summary of data submitted to comply with nontarget organism data requirements 

published in 40 CFR § 158.2150 for support of the registration of Phoma macrostoma strain 94-

44B. 

Data Requirement OCSPP 

(OPPTS) 

Guideline No. 

Results Summary and Classification MRID No. 

Avian oral 

toxicity/pathogenicity 

885.4050 The 30-day oral LD50 was > 2.22 × 105

CFU/kg bw/day. 

Classification: Supplemental; adequate for 

EPA risk assessment1

479150-18 

Avian inhalation 

toxicity/pathogenicity 

885.4100 Not required; Phoma macrostoma is not 

known or shown to be an avian pathogen 

N/A 

Wild mammal 

toxicity/pathogenicity 

885.4150 Rationale states that P. macrostoma is 

ubiquitous and P. macrostoma 94-44B has 

been shown to decline in population after 

application. An acute oral toxicity study with 

laboratory rats estimated an LD50 of > 108

CFU/animal, no adverse effects observed. 

Classification: Acceptable rationale 

479150-26 

Freshwater fish 

toxicity/pathogenicity 

885.4200 The 32-day LC50 was >2.9 × 103 CFU/mL; no 

adverse effects were observed during the 

study. 

Classification: Acceptable 

479150-19 

Freshwater 

invertebrate 

toxicity/pathogenicity 

885.4240 The 21-day EC50 was > 3.78 x 102 CFU/mL. 

The NOAEC based on growth and 

reproduction was 2.71 × 103 CFU/mL. 

Classification: Acceptable 

479150-20 

Estuarine/marine fish 

and invertebrate 

testing 

885.4280 Not required – significant concentrations are 

not expected to reach marine/estuarine 

environments as a result of the proposed uses. 

N/A 

Nontarget insect 

testing 

885.4340 Green lacewing: The 15-day LC50 was > 1 × 

106

 CFU/mL diet 

Lady bird beetle: The 12-day dietary LC50 > 

1 × 106

 CFU/mL diet. 

Parasitic hymenoptera: The 16-day dietary 

LC50 > 1 × 106

 CFU/mL. 

Classification: All studies are acceptable 

479150-23 

479150-24 

479150-22 

Honey bee testing 885.4380 The 5-day LC50 was >1 × 106 CFU/mL diet. 

The study was not long enough to assess 

pathogenicity. 

Classification: Supplemental; adequate for 

risk assessment 

479150-25 
4

Data Requirement OCSPP 

(OPPTS) 

Guideline No. 

Results Summary and Classification MRID No. 

Nontarget plant 

testing 

885.4300 Aquatic (Lemna gibba): The 7-day EC50 = 

1.51 × 104 CFU/mL; the NOAEC = 4.4 × 103

CFU/mL. 

Terrestrial: A collection of studies showed 

that P. macrostoma strain 94-44B is 

toxic/pathogenic to several species of 

terrestrial broadleaf plants. 

Classification: Both studies are acceptable 

479150-21 

483184-01 

1

Viability of the test substance was not confirmed, which is necessary for an “Acceptable” rating from PMRA. The 

study is acceptable for risk assessment. 

 C. Ecological Exposure and Environmental Risk Characterization 

1. Terrestrial Animals and Plants 

The EPs are to be applied pre- or post-emergence in spot or broadcast treatments to control 

various broadleaf weed species to ornamentals, turf, and impervious surfaces such as driveways 

and patios. Ornamental uses include applications to flowers, roses, ground covers, shrubs, trees, 

and ornamental grasses, as well as container grown plants, field grown nurseries, and landscapes, 

and the labels provide lists of specific tolerant and susceptible ornamental plants and grasses. 

Specific use sites for turf (e.g., sod farms, golf courses) are not provided, and should be clarified 

on the label. Spot treatments are applied at a maximum rate of 2 grams/0.35 ft2 (8-inch diameter 

circle), and broadcast applications are made at a maximum rate of 8 lbs/1000ft2. The labeled 

viability of the Phoma macrostoma strain 94-44B for the EPs is 103 CFU/g product, therefore 

spot applications result in approximately 5.7 x 103

 CFU/ft2 and broadcast applications result in 

approximately 3.6 x 103 CFU/ft2 at application. The application methodology and equipment 

must be clarified on the label. 

Environmental Fate and Persistence

The applicant submitted studies from peer-reviewed journals as rationale to waive higher tier 

testing on nontarget plants. These studies provided data and information regarding the 

environmental fate of Phoma macrostoma strain 94-44B and macrocidins and its bimodal 

pesticidal activity as a wound pathogen and macrocidin release into colonized plant tissues or 

surrounding soil. 

Zhou et al. (2004) reported the fate of several strains of Phoma macrostoma used as herbicides in 

the terrestrial environment, including strain 94-44B. In this study, Phoma macrostoma (a 

different strain than the one proposed for registration) was used to treat small field plots, and it 

was rarely detected in adjacent untreated areas 30 cm beyond the boundaries of the treated plots. 

The authors also noted the tendency of the test material to drift, which was a likely reason it was 

found outside the plots. In soil, Phoma macrostoma strain 94-44B PCR detections declined over 

time, but the number of viable propagules also started to decline. These trends of Phoma 

macrostoma-PCR detections continued the following year, and susceptible species planted the 

following year did not show effects expected as a result of infection by Phoma macrostoma 
5

strain 94-44B. The authors noted that P. macrostoma is considered as a poor competitor, and the 

ability for the fungus to grow is restricted in soils with higher microbial activity. 

Bailey et al. (2011b) show that macrocidins are partially soluble in water, and may run off from 

areas of application under some conditions (e.g., with saturated soils). This work was 

inconclusive with respect to the ability of Phoma macrostoma to mobilize with runoff, but the 

authors deduced from the available data that the fungus was less likely to be as mobile in soil as 

the macrocidins. Phoma macrostoma also is not expected to move very far via natural dispersal 

once it is applied, since Phoma macrostoma is primarily dispersed by rain splash (Bailey et al. 

2010). 

Both Zhou et al. (2004) and Bailey et al. (2011b) showed that Phoma macrostoma strain 94-44B 

colonizes both susceptible and resistant plants. However, the infection process and subsequent 

colonization of roots from susceptible plants appears to be different from roots of resistant plants 

(Bailey, et al., 2011b). Phytotoxic macrocidins are produced only by mycelia of Phoma 

macrostoma and not conidia (Graupner et al., 2006), although excess quantities may be exuded 

to the surrounding growth medium (Graupner et al., 2003). Granular formulations of P. 

macrostoma strain 94-44B encourage root infection through root hairs and uptake of phloemmobile compounds by the plant roots after mycelia reach the rhizospheres of treated plants 

(Bailey, et al., 2010). Fungal mycelia infect the inner tissues of the root core by breaking down 

internal cellular structures of susceptible plants (e.g., dandelion) and simultaneously producing 

additional phytotoxins, further damaging the vascular system of susceptible plants. In contrast, 

resistant plants (e.g., barley) show restricted fungal growth within the root and are asymptomatic 

of photobleaching, further supporting the combined effects of at least two modes of herbicidal 

activity (Bailey, 2010). Photobleaching has only been reported for susceptible plants where the 

mycelia were observed to colonize and disrupt the central vascular core of root tissues of 

susceptible plants. Therefore, it is the combined role of infection and the presence of 

macrocidins that have direct effects on the plant. 

Colonized plants that survive may serve as reservoirs of Phoma macrostoma strain 94-44B that 

would be available to cause future effects to susceptible nontarget plants where conditions allow. 

However, these conditions would need to be maintained to promote persistence, since only an 

asexual life stage has been found for Phoma macrostoma (Bailey et al. 2010). Survival structures 

such as sclerotia have not been reported for Phoma macrostoma. Zhou et al. (2004) showed that 

after one year, the fungus could only be detected in 12% of non-susceptible plant root samples 

from treated areas (in contrast to 5% of controls). However, chlorosis (presumably from 

macrocidin) was seen in sunflowers planted into a treated site one year after treatment, although 

there may be other biological or environmental factors that caused the chlorosis in sunflowers. 

(Bergstrom, 2011). 

Environmental Fate Conclusions: The environmental fate data indicate that Phoma macrostoma

strain 94-44B is unlikely to persist at high levels for long periods of time or move great distances 

when applied to turf and ornamentals. The reviewers make the following conclusions with 

respect to environmental fate of Phoma macrostoma strain 94-44B: 
6

• The proposed labels include optional language for some uses that encourage users to 

apply the products on a calm day. Calm conditions (e.g., wind speed < 5 mph) should be 

required on the label for all applications. If these label instructions are followed, a 

relatively small amount of Phoma macrostoma strain 94-44B is expected to drift, and 

only to within the margins around the treated area. 

• Bailey et al. (2011b) show that macrocidins may be mobilized by runoff when soils are 

saturated; therefore, some movement into adjacent areas could occur via this process. 

Label language should be included that requires the user to immediately water in the EP 

at application, but not to the level of soil saturation. If this language is included, runoff 

into adjacent areas as a result of applications to turf and ornamentals is expected to be 

minimized. Care should also be taken to not apply these products when soils are 

saturated (Bailey, et al., 2010). 

• Significant runoff is expected with applications to impervious surfaces; therefore, the 

reviewers recommend that these applications should be removed from the proposed 

labels. 

• Persistence is expected within treated areas with repeated applications. Studies show a 

declining trend after four months and survival of susceptible plants after one year has 

varied. Therefore, Phoma macrostoma strain 94-44B may persist within treated areas. 

Birds and Mammals

The primary route of exposure of birds and mammals to Phoma macrostoma strain 94-44B is 

likely through direct consumption of the EP. The avian LD50 was determined > 2.22 × 105

CFU/kg bw/day for Northern bobwhite (Colinus virginianus), and no adverse effects were 

observed at this maximum hazard dose after 5 days of exposure at this dose and an additional 25 

days of observation (total dose 1.1 x 106

 CFU/kg bw). An acceptable LD50 for laboratory rats 

was determined to be > 1 x 108 CFU/animal, and no adverse effects were observed during the 21 

day study (MRID 47915008). Based on these results, adverse effects to birds and wild mammals 

as a result of the proposed applications of the EPs are not expected. 

 

Nontarget Insects and Honey Bees

Some species of nontarget insects could be exposed to Phoma macrostoma strain 94-44B 

through consumption of granules, consumption of treated plant tissues, or through cuticular 

contact in treated soils. Since Phoma macrostoma is not reported as an insect pathogen, 

cuticular contact with viable conidia or mycelia of the fungal product is not expected to be a 

realistic route through which Phoma macrostoma strain 94-44B could infect an insect or other 

terrestrial arthropod. 

Three species of beneficial nontarget insects were exposed to Phoma macrostoma strain 94-44B 

mycelia through the diet. These species were green lacewing (Chrysoperla rufilabris), lady bird 

beetle (Hippodamia convergens), and a parasitic wasp (Pediobius foveolatus). The LC50 was 

determined to be > 1x 106

 CFU/mL diet for each species, and significant adverse effects were not 

observed. Based on this testing, adverse effects to nontarget insects are not expected to result 

from dietary exposure to Phoma macrostoma strain 94-44B. 
7

The submitted honey bee study showed that Phoma macrostoma strain 94-44B was not toxic to 

honey bees at a dose of 1 x 106 CFU/mL diet over five days. The study was determined to be 

supplemental because it was of short duration to allow for determination of pathogenicity. 

However, since exposure is expected to be low for bees, and because no reports have been found 

in which Phoma macrostoma was identified as a bee or other insect pathogen, adverse effects in 

bees are not expected to occur as a result of the proposed labeled applications. 

Nontarget Terrestrial Plants

Phoma macrostoma is considered to be a weak or wound pathogen, existing primarily as a 

saprobe. Summaries of efficacy studies with terrestrial species of plants were submitted to satisfy 

the nontarget plant data requirements (MRID 48318401). These studies showed that many 

broadleaf plants were susceptible to Phoma macrostoma strain 94-44B, and susceptibility varied 

among species. Grass and related monocotyledonous species were not shown to be susceptible, 

but other types of monocot species were not tested. More recent information from the open 

literature noted that P. macrostoma strain 94-44B was pathogenic to many dicotyledonous plant 

species, but nonpathogenic to the species of monocots that were tested (Bailey et al., 2011a). 

Specifically, of the 75 plant species in 22 plant families studied, seven plant families were not 

adversely affected by P. macrostoma 94-44B (Salicaceae, Pinaceae, Iridaceae, Curcurbitaceae, 

Solanaceae (bell pepper, tomato), Linaceae, Graminae), whereas Phoma macrostoma 94-44B 

caused chlorosis and mortality in species from 16 plant families (Convolvulaceae, Lythraceae, 

Polygonaceae, Rubiaceae, Euphorbiaceae, Caryophyllaceae, Brassicaceae, Amaranthaceae, 

Labiatae, Lamiaceae, Leguminosae/Fabaceae, Rosaceae, Plantaginaceae, Asteraceae, 

Balsminaceae, Solanaceae (petunia)). Most applications were pre-emergent, though postemergent applications were made in two of the studies, and both lethal and sublethal effects were 

observed with both types of application. These effects primarily included chlorosis and 

mortality; some studies also measured biomass and emergence. Several studies examined the 

effects of multiple inoculum levels. Mortality and other effects were generally dose dependent 

in susceptible species, and sublethal effects (mainly chlorosis) were observed in some studies at 

the lowest rate tested (stated to be as low as 1/8x EP application rate). The study authors noted 

that chlorosis did not necessarily predict mortality. 

The weight of evidence to date suggests that the microbial active ingredient is a weak pathogen, 

affecting susceptible species of several plant families primarily in the dicots (MRID 48318401; 

Bailey, et al., 2011a). It is also considered to be a poor competitor (Zhou, et al., 2004) and soils 

with enhanced microbial activity will likely restrict the ability of the biocontrol fungus to grow. 

Phoma macrostoma does not appear to be related to the soybean red blotch pathogen (Phoma 

glycinicola) or other more potent crop pathogens such as P. lingam (pathogenic to species in the 

Brassicaceae) (implied in Zhou et al., 2004; opinion provided by Bergstrom, 2011). Therefore, 

the reviewers make the following conclusions regarding nontarget plants: 

• Adverse effects may occur to susceptible nontarget plants in areas treated with the 

mycoherbicide. This is of particular concern for rotational dicotyledonous plants that 

may be planted into a previously treated area (Bergstrom 2011). 

• Effects to nontarget plants beyond the treated sites are expected to be limited to 

immediately adjacent areas for applications to turf and ornamentals. Widespread losses of 
8

plants, such as might be seen with a broad-spectrum chemical herbicide, are not 

expected; however, species of significant economic or ecological importance could be 

affected if they are susceptible. If the product is applied according to the label language 

recommended above, the species affected in these areas is expected to be very limited. 

• Applications to impervious surfaces may result in significant effects to nontarget plants if 

runoff occurs. 

 

2. Aquatic Animals and Plants 

Exposure in the Aquatic Environment

Since it is assumed the EP can drift or run off, it is possible Phoma macrostoma strain 94-44B or 

macrocidins can move to aquatic areas. The spot application for turf and ornamentals (2 g/8-in 

circle or 5.7 x 103

 cfu/ft2) would produce the maximum possible concentration in water if applied 

continuously over a body of water. So, if 5.7 x 103 cfu/ft2 were applied to the EPA Standard 

Wetland (a 1-ha body of water that is 15 cm deep), this would produce a concentration of Phoma 

macrostoma strain 94-44B of 0.41 cfu/mL. This is below reported concentrations of Phoma

species or total fungal counts containing Phoma species reported in some surface waters (e.g., 

Abdel Hameed et al. 2008, Pereira et al. 2009). Drift and runoff would occur at a fraction of this 

maximum possible amount; therefore, concentrations of Phoma macrostoma strain 94-44B and 

its macrocidins present at application are not likely to reach freshwater or marine/estuarine 

habitats in significant concentrations. 

Freshwater fish

A 32-day study with rainbow trout (Oncorhynchus mykiss) showed that the LC50 is > 2.9 x 103

CFU/mL (measured) for freshwater fish. The test subjects in this study were exposed through 

both the test water and the diet for the duration of the study, and no lethal or overt sublethal 

effects were observed. The exposure amount was well above the maximum hazard dose, and it 

was determined that Phoma macrostoma strain 94-44B is not toxic or pathogenic to freshwater 

fish. Since the test material contained a low amount of macrocidins, it is not necessarily a test of 

the potential hazard of these metabolites to fish; however, the study is acceptable for use in 

regulatory risk assessment. Based on the expected low exposure and the results of this study, 

adverse effects to freshwater fish are not expected to result from the proposed applications of 

Phoma macrostoma strain 94-44B. 

Freshwater invertebrates

A 21- day study with Daphnia magna was submitted, which provided an estimated EC50 of 

>3.78 x 102 CFU/mL (measured). The NOAEC for reproduction and growth (length and dry 

weight) was 2.71 × 103 CFU/mL and the LOAEC was 4.22 × 103 CFU/mL. A dose-response 

relationship was not evident based on mortality, reproduction, or growth. Effects were observed 

in the attenuated control group, such that mortality was 100% by the end of the test. The study 

authors noted that the test solutions at high concentrations, including the attenuated control, were 

cloudy and that some of the test material settled on the bottom of the test vessels. This was also 

observed in the study with rainbow trout described above, and is not uncommon in aquatic 
9

testing with fungal MPCAs. It is likely that the effects observed in this study are due to the 

turbidity resulting from high concentrations in the test water and not the test material. However, 

the test material contained a low amount of macrocidins, so the toxicity of these metabolites was 

not necessarily tested. The measured values tested are not quite above the maximum hazard 

concentration suggested by OCSPP (OPPTS) guidelines for aquatic testing with MPCAs; 

however, the EC50 value is 920X the maximum possible concentration in water and the NOAEC 

is 1030X this concentration. Therefore, because of low expected exposure and the lack of 

toxicity/pathogenicity of the fungus, adverse effects to freshwater invertebrates are not expected 

to result from the proposed labeled applications of Phoma macrostoma strain 94-44B. 

Freshwater aquatic plants

A study with Lemna gibba showed that the 7-day EC50 = 1.51 × 104 CFU/mL (measured) for 

Phoma macrostoma strain 94-44B. The NOAEC was 4.4 × 103 CFU/mL and the LOAEC was 

9.5 × 103 CFU/mL (measured). The test substance caused some necrotic fronds and a significant 

inhibition in frond number and biomass at the higher tested concentrations as compared to that 

seen in the lower test concentrations. Therefore, Phoma macrostoma strain 94-44B is likely to 

cause effects to aquatic plants if it is deposited in water in significant amounts. The measured 

concentrations tested in the Lemna study, however, are above the maximum hazard dose of 413 

CFU/mL, and are well above the maximum environmental concentration of 0.413 CFU/mL. 

Therefore, since the concentration resulting from offsite movement is not expected to be 

significant, adverse effects to aquatic plants as a result of the proposed labeled applications of 

Phoma macrostoma strain 94-44B are not expected. 

Marine/estuarine animals and plants

Phoma macrostoma strain 94-44B is not expected to reach marine/estuarine environments in 

significant amounts. Therefore, adverse effects to plants and animals in this environment are not 

expected. 

3. Open Literature Information for Nontarget Organisms Other Than Terrestrial 

 Plants 

Literature searches were performed to determine if other effects have been reported that were not 

contained within the information provided by the registrant. A search was performed with the 

Environmental Information Search service available to the Agency. This search tool 

simultaneously queries the Agricola; Biosis Previews; CAB Abstracts; Energy, Science, and 

Technology, General Science Abstracts, and National Technical Information Service databases 

within the years of 1926 – present. A search was performed with the term ‘Phoma macrostoma’ 

was performed and returned 67 records. No additional records of effects to nontarget organisms, 

other than the effects to plants already reported were found. The search term ‘Phoma’ was also 

paired individually with the terms, ‘bird,’ ‘mammal,’ insect,’ ‘arthropod,’ ‘arachnid,’ ‘aquatic,’ 

‘bivalve,’ ‘invertebrate,’ ‘fish,’ ‘reptile,’ ‘amphibian,’ and ‘crustacean,’ and no additional reports 

of toxicity or pathogenicity related to Phoma macrostoma were found for these taxa. 

Additionally, ‘macrocidin’ was searched within these databases, and no additional information 

was found as to its potential toxicity on nontarget organisms. 
10

4. Data Uncertainties 

The test material for most of the nontarget studies (except for birds) contained very low levels of 

macrocidins. BPPD concluded that risk of adverse effects is low to nontarget insects and 

honeybees for the proposed applications of Phoma macrostoma strain 94-44B, but that the 

potential toxicity of macrocidins present in the EPs is not known and presents some uncertainty 

in the risk assessment. An additional study with honeybee or other nontarget insect species 

would clarify the potential hazard of macrocidins to these nontarget species; however, additional 

data are not required at this time. 

 

The environmental persistence of viable Phoma macrostoma is anticipated to be of relatively low 

risk in most turf environments as provided on the proposed labels. The level and relative 

persistence of macrocidins in the environment following application(s) is also uncertain. 

Therefore, it is recommended that the labels be revised and clarified with respect to appropriate 

text to mitigate drift and runoff to adjacent lands that have plants of agricultural or conservation 

significance. Specific turf use sites should be clarified on the label. 

D. Threatened and Endangered Species Assessment 

Direct Effects

Adverse effects on terrestrial vertebrates, nontarget insects, and freshwater and marine/estuarine 

animals and plants are not expected to occur due to exposure resulting from all proposed labeled 

applications of Phoma macrostoma strain 94-44B. Therefore, a “No Effect” determination is 

made for direct effects to federally listed threatened and endangered (listed) species within these 

taxa as a result of all proposed applications as labeled. 

While the proposed applications are not expected to result in widespread losses of nonlisted 

nontarget terrestrial plants, the potential for sublethal or lethal effects to individual listed 

terrestrial plants cannot be precluded. The potential occurrence of listed plants on the treated 

areas may be unlikely, but it is unknown. Drift or runoff of the EP, especially with applications 

to impervious surfaces, may also deposit Phoma macrostoma strain 94-44B in areas containing 

listed plants. Even though exposure may not result in mortality, it can cause sublethal necrosis 

and chlorosis that may contribute to reduced survival and reproduction of a listed plant. 

Therefore, the proposed applications of Phoma macrostoma strain 94-44B have the potential to 

directly affect individual listed terrestrial plants. Further analyses are needed to determine the 

extent of effects and species affected. 

Indirect Effects and Effects to Critical Habitat

Effects to terrestrial vertebrates, nontarget insects, and freshwater and marine/estuarine animals 

and plants are not expected to occur as a result of proposed applications of Phoma macrostoma

strain 94-44B. Therefore, indirect effects to listed species dependent on these taxa and related 

effects to their Critical Habitat are not expected and a “No Effect” determination is made for 

indirect and habitat effects to listed species dependent on these taxa for all proposed applications. 
11

The proposed applications of Phoma macrostoma strain 94-44B are not expected to result in 

widespread effects to nonlisted terrestrial plants, so indirect effects to listed generalist species 

dependent on plants are not expected, and EPA makes a “No Effect” determination for indirect 

and habitat effects to all listed species that do not have an obligate relationship with any 

particular species of plant. Significant effects may occur in certain susceptible plant species, so 

applications of Phoma macrostoma strain 94-44B could affect a nonlisted (or listed) plant upon 

which a listed species depends exclusively for food or habitat. Therefore, applications of Phoma 

macrostoma strain 94-44B have the potential to cause indirect effects to listed species and also 

Critical Habitat for listed species with obligate relationships to susceptible plants. Further 

analyses will be necessary to determine the extent of effects and species affected. 

II. Environmental Assessment Conclusions 

BPPD has performed an environmental risk assessment for Phoma macrostoma strain 94-44B 

based on the data provided by the applicant and studies from the open literature, and has made 

the following conclusions: 

1. Exposure of nontarget organisms to Phoma macrostoma strain 94-44B and/or macrocidins 

may occur in the terrestrial environment as a result of the proposed applications. For turf and 

ornamental applications, exposure is expected to be limited to the treated site and 

immediately adjacent area if additional language is included on the label (see below). Longterm use in treated areas may lead to effects on susceptible rotational crop species. 

Significant offsite movement and nontarget exposures are expected with applications to 

impervious surfaces (e.g., patios, driveways, sidewalks), and the reviewers recommend that 

these uses be removed from the proposed label. 

2. Significant exposure of nontarget organisms to Phoma macrostoma strain 94-44B and/or 

macrocidins is not expected in aquatic environments. 

3. Adverse effects to birds, wild mammals, nontarget insects, honey bees, freshwater fish and 

invertebrates, marine/estuarine fish and invertebrates, and aquatic plants are not expected. 

4. Some species of nontarget plants may be adversely affected where significant exposure 

occurs. 

• Nontarget plant effects may be significant for susceptible species in treated areas, 

where its herbicidal effect is intended, which may be a concern for susceptible 

rotational dicotyledonous plants 

• Effects to nontarget plants beyond the treated sites are expected to be limited to 

immediately adjacent areas for applications to turf and ornamentals, and effects will 

be limited to more highly susceptible species. Additional label language is suggested 

below. If these are included in the label, effects on nontarget plants are expected to 

be very limited. 

• Applications to impervious surfaces may result in significant effects to nontarget 

plants if runoff occurs. 
12

5. The following conclusions are made for listed species 

• A “No Effect” determination is made for 

o Direct effects to listed birds, wild mammals, insects, honey bees, freshwater fish 

and invertebrates, marine/estuarine fish and invertebrates, and aquatic plants. 

o Indirect effects and effects on designated Critical Habitat for listed species 

dependent on birds, wild mammals, insects, honey bees, freshwater fish and 

invertebrates, marine/estuarine fish and invertebrates, and aquatic plants. 

o Indirect effects and effects on designated Critical Habitat for all listed species that 

do not have an obligate relationship with any particular species of plant. 

• The proposed applications of Phoma macrostoma strain 94-44B have the potential to 

directly affect individual listed terrestrial plants. The proposed applications also have 

the potential to cause indirect effects to listed species and also Critical Habitat for 

listed species with obligate relationships to susceptible plants. Further analyses will 

be necessary to determine the extent of effects and species affected. 

6. The following changes to the proposed label should be made to reduce terrestrial nontarget 

exposure: 

• The EPs must be applied on calm days (e.g., wind speed is < 5 mph) to minimize drift 

• The EPs must be immediately watered in with all applications to turf and ornamentals 

• Applications to impervious surfaces should be removed from the label. 

7. The Agency may require additional testing if uses are expanded, if formulations change for 

the end-use products, or if incidents of adverse effects to nontarget organisms occur during 

commercial use of these products. 

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