College of Tropical Agriculture Extension PUBLICATIONS and Human Resources University of Hawai‘i at manoa

Dallisgrass Offers Benefits But Beware of Poisoning!

Background and 2b), Stargrass (Cynodon Distribution nlemfuensis, Figure 2c) and the Brachiaria hybrids, Dallisgrass ( dil- Mulatto I and Mulatto II. atatum) is a warm-season, Suitable companion legumes perennial forage native to include Kaimi clover (Des- South America (southern modium incanum, Figure Brazil, , Paraguay, 2d), Siratro (Macroptilium Uruguay, etc.), and is an atropurpureum), Glycine important grass for livestock (Neonotonia wightii, production in pastures Figure 2e) and Seca stylo across the state of Hawai‘i. (Stylosanthes scabra). At Dallisgrass grows well in a higher elevations (> 2500’), variety of clay, red loam, Ladino white clover (Trifo- and sandy soils with a pH lium repens) is a suitable range of 5.5 to 7.0, in areas companion. Dallisgrass of the state supported by seed sown with plantain 30-60 inches of annual (Plantago lanceolata), a rainfall. Figure 1 shows test high protein (14-24% crude plots and pastures on Maui where Dallisgrass has become a protein) broadleaf that is quick to establish, is another primary forage species. option to increase forage diversity (Figure 2f). Dallisgrass is known for being fast growing, and very adaptable, as its abundant rhizomes and deep, fibrous Usage root system confer tremendous drought-resistance and The forage quality and overall palatability of Dallisgrass erosion control properties [1]. Furthermore, strong stands is very good for most grazing livestock. Consequently, of Dallisgrass pastures have been established on Maui in cattle and sheep will graze it very closely unless man- former pineapple plantations, with soil pH ranging from aged with rotational grazing. In mixture pastures where 4.2-4.5 (Pi‘iholo, Hali‘imaile, Haiku-Pauwela and Peahi Dallisgrass is a primary forage species, the stocking rate sites). for cow calf pairs is markedly improved over previously Planting Recommendations existing like Hilo grass (Paspalum conjugatum Dallisgrass can be planted into either a tilled, prepared seedbed by broadcast or a no-till drill into a killed sod or grass stand. A seeding rate of 10-15 pounds per August 2021 acre (drilled) or 18-25 pounds per acre (broadcast) is Subject Category: Animal Sciences, AS-6 recommended. Results of several test plots indicate the optimum time for planting is between March 15 and Kyle C. Caires, PhD June 15. Though Dallisgrass contains rhizomes, they are Department of Human Nutrition, highly inactive in terms of growth, therefore, planting of Food, and Animal Sciences seed is preferred. [email protected], (541) 760-6317 Attaining pure stands of Dallisgrass is difficult due to This information has been poor germination of seed, but it is found to be excellent reviewed by CTAHR faculty in mixtures of Bahiagrass (Paspalum notatum Flugge, Figure 2a), Bermuda grass (Cynodon dactylon, Figure rates (30-, 60-, 90-, 120- and 150-lbs/acre) in early July, then ratoons were harvested at 25- and 60-days post-treatment; these experiments were repeated the following year (Figure 4). Spoon feeding with 25-30 pounds N/acre at intervals on an as-needed basis is recommended, with forage yields achieved at a cost of $9.59/ton as fed, or $40.31/ton on a dry-matter basis (Figure 4). Fertilization beyond 30 pounds N/ acre results in diminishing returns that will continue as commercial fertilizer costs remain high (Figure 4). Also, Dallisgrass responds quickly to irrigation during dry months or drought, without fear of grass tetany ob- served in other fast-growing grasses.

Berguis) or Vasey grass (Paspalum urvillei), or even common Bermuda grass stands. Ranchers have had much success harvesting Dallisgrass in green-chop applications to provide roughage for local feedlots and emergency pastoral supplementation during times of drought (Figure 3). Although the yields are lower, the benefits are many: harvesting Dallisgrass when is it young and growing rapidly provides a 12-18% crude protein feedstuff in a green-chop application, with low agronomic input requirements, on a ratoon (regrowth) schedule of 25-33 days (before seed head formation), provided that cutting depths were not too In years with adequate rainfall, and during the rainy seasons, low, leaving at least 3-4 inches of stubble. matu- Dallisgrass and Dallisgrass mixtures have been success- ration occurs faster in Hawai‘i (75-90 days), than what fully harvested to produce an abundance of silage and is observed on the U.S. Mainland and southern Brazil wrapped baleage (Figure 3) in order to stockpile forage for [1-2]. feeding during the dry summer months and winter dor- mancy observed in other local, warm season grasses such Dallisgrass responds well to nitrogen fertilizer without as Pangola (Digitaria eriantha). the fear of nitrate toxicity. To determine the optimum fertilization levels, an experiment was conducted in In theory, Dallisgrass could also be cut to make dry hay, 2019 in which test plots were clipped to 4 inches (10 but in practice, we observed poor dry down and slow wilt cm) and fertilized at differing nitrogen (N) application characteristics, making it undesirable for that application. College of Tropical Agriculture Extension PUBLICATIONS and Human Resources University of Hawai‘i at manoa

Ergot Poisoning and Dallisgrass Staggers Dallisgrass is a good-quality, warm-season perennial for permanent pasture systems, but the one major drawback of this forage is the potential for “Dallisgrass Staggers,” a type of poisoning caused by an ergot-like fungus called Claviceps paspali, which parasitizes the seed heads of Dal- lisgrass. Infected Dallisgrass seed heads contain several tremorgenic mycotoxins [2] that are alkaloids in nature, including Paspalinine, Paspalitrem A and Paspalitrem B. Drawings representing the 2-D structure of each tremor- genic mycotoxin [3-5] is shown in Figure 5. It is known that ergot alkaloids produced by Claviceps paspali fungi are small lipophilic molecules and lysergic acid derivatives [6] that easily permeate the blood-brain barrier in vitro [7], leading to various neurotoxic effects. The first reported case of ergot poisoning in cattle grazing on Dallisgrass was in 1967 [8], but reports indicate sheep [9] and horses [10] are also affected. The mode of action of these fungal mycotoxins is not fully understood, but affected animals consuming these compounds demonstrate remarkable neurological symp- toms, including trembling of the head and neck, erratic uncontrolled and uncoordinated movements in the rear limbs, and sometimes acting very fractious and aggres- Furthermore, the dark-brown appearance of Dallisgrass sive. Affected animals will startle easy, run abruptly, fall in bales after dry-down make it hard to distinguish from randomly, and may remain non-ambulatory for hours weeds and less desirable grasses. Dallisgrass is a valuable or even, days. Advanced cases include animals with component in a mixed, warm-season perennial pasture, violent tremors that may lead to death. Sometimes the but special management considerations must be followed sudden-death condition is mistakenly attributed to Grass to ensure the health and welfare of the livestock it is tetany. intended to support.

page 3 Dallisgrass Staggers has been observed on several ranches same pastures and exhibited signs of ergot toxicity at a in Maui and Hawai‘i counties in 2018 and 2019. In all higher rate (unpublished observations). cases reported, infected Dallisgrass seed heads were Infected Dallisgrass seed heads are usually found in situ- shown to have negative effects on cattle and sheep ations when ranchers (1) graze small numbers of cattle or grazing those pastures (Figure 6). A recent case in 2021 sheep in large pastures, (2) keep a paddock or pasture in found strong indications that the tremorgenic mycotoxins an extended rest period hoping to achieve greater forage in infected Dallisgrass seed heads induced abortions volume, or (3) stockpile grass. In any case, the Dallisgrass in first-calf heifers, during the 1st and 2nd trimesters of was able to grow, bloom, and mature, seeding out faster pregnancy, within several days of consumption [11]. Anec- than the livestock could consume it. dotal observations tend to indicate that cattle 4 years of age and younger to be the most affected, suggesting The normal prevalence of infected seed heads is more that cattle over time may learn to avoid grazing infected commonly observed from early June to mid-August. seed heads. In 2019, Katahdin and St. Croix hair sheep Hawai‘i’s unique subtropical climate allows for a wider were observed to be less affected by mature Dallisgrass, distribution of this condition than the southeastern United in comparison to Suffolk and Hampshire ewes grazing the States. Expect large changes in prevalence of ergot infection during transitions to El Niño, and following wet seasons starting with a strengthening La Niña. In the latter case, the wet weather in late July and early August exacerbates the growth and spread of ergot fungus in Dallisgrass stands. From observation, the ergot fungus will target other grass species, such as Bahiagrass (Paspalum notatum), but Dallisgrass stands are the most susceptible to infection. Management and Prevention of Ergot Poisoning Mixed Dallisgrass pastures should be inspected for the presence of ergot-infected seed heads before introducing livestock, as a best management practice (Figure 6). Rotational grazing systems should be utilized with enough stock density to ensure that Dallisgrass is consumed in the vegetative and early bloom stages, to maximize animal productivity and minimize the risks of ergot infection. In a silage, baleage, or green-chop operation, frequent and short cuttings during summer months is recommended to suppress seed head formation, thereby reducing the opportunity for toxic exposure events to livestock. When the stockpiling of forage is desired in pastures with an abundance of Dallisgrass, mechanical clipping (rotary or flail-chopping mower) at height of 10-12 inches (25-30 cm) to remove the seed heads is recommended, prior to the introduction of animals for grazing. Like any ergot toxicity affecting livestock, no treatment exists for Dallisgrass Staggers [12]. The best management strategy for affected animals is to move them to a pasture without infected grass and provide high-quality grass, hay or silage for them to consume; if done early enough, infected cattle can completely recover from the poisoning event. To prevent injury and drowning, affected cattle should not to be moved to areas with steep terrain, large gulches, or open water sources likes streams, ditches, or ponds. College of Tropical Agriculture Extension PUBLICATIONS and Human Resources University of Hawai‘i at manoa

Conclusion Paspalinine. https://pubchem.ncbi.nlm.nih.gov/com- Dallisgrass is a rapidly-growing, warm-season perennial pound/Paspalinine. Accessed Aug. 7, 2021. grass for the humid lowland pastures of Hawai‘i, but 4. National Center for Biotechnology Information. special management is required to prevent the harmful PubChem Compound Summary for CID 10028978, effects of ergot poisoning in various forage systems – Paspalitrem A. https://pubchem.ncbi.nlm.nih.gov/ more so during the summer months – including graz- compound/Paspalitrem-A. Accessed Aug. 7, 2021. ing, green chop and silage/baleage systems. When 5. National Center for Biotechnology Information. (2021). establishing new stands, consider planting a mixture of PubChem Compound Summary for CID 102143871, compatible grass and companion legume species that Paspalitrem B. https://pubchem.ncbi.nlm.nih.gov/ are suited to the rainfall and soil characteristics of the compound/Paspalitrem-B. Accessed Aug. 7, 2021. proposed site. This strategy will promote forage diversity, 6. Selala MI, Daelemans F, Schepens PJ. (1989). Fungal minimize any negative effects of ergot infection, and tremorgens: the mechanism of action of single ensure year-round productivity of the stand for grazing, nitrogen containing toxins - a hypothesis. Drug and green-chop, or silage/baleage production. Dallisgrass is chemical toxicology, 12(3-4), 237–257. tolerant to environmental stressors (drought and frost) 7. Mulac D, Hüwel S, Galla HJ, Humpf HU. (2012) Perme- and exhibits higher forage quality than most C4 grasses, ability of ergot alkaloids across the blood-brain barrier making it an attractive candidate as a feedstuff for in vitro and influence on the barrier integrity. Mol Nutr ruminants involved in dairy and meat production within Food Res. 56(3):475–485. the tropics and subtropics. 8. Goodwin DE. (1967). Ergot poisoning of cattle grazing Dallisgrass. Journal of the American Veterinary Medical Productivity losses due to ergot infection and abiotic Association, 151(2), 204–205. stresses (salinity, environmental extremes, etc.) are known, 9. Mantle PG, Mortimer PH, White EP. (1978). Mycotoxic necessitating the need for gene discovery and molecular tremorgens of Claviceps paspali and Penicillium marker development, such that improved cultivars of Dal- cyclopium: a comparative study of effects on sheep lisgrass and other members of the Paspalum genus could and cattle in relation to natural staggers syndromes. be created to overcome those inherent obstacles. A group Research in Veterinary Science, 24(1), 49–56. of researchers from Australia and Argentina have recently 10. Caires KC (2021). Opportunities and challenges for IVF sequenced the Dallisgrass genome [13]. This collaborative to improve Hawai‘i’s grass-finished beef industry effort represents a major step toward a better understanding [Conference presentation]. In Vitro Production of of the biomarkers associated with agronomic traits in Bovine Embryos: From Theory to Practice. University Paspalum grasses, which may lead to improved cultivars of Passo Fundo. Rio Grande do Sul, Brazil. May 26 for use in livestock production. 11. Cawdell-Smith AJ, Scrivener CJ, Bryden WL. (2010). References Staggers in horses grazing paspalum infected with Claviceps paspali. Australian Veterinary Journal, 1. Cook BG, Pengelly BC; Brown SD, Donnelly JL, Eagles 88(10), 393-395 DA, Franco MA, Hanson J, Mullen BF, Partridge IJ, 12. McMullen, M. Stoltenow, C. (2002). Ergot. NDSU Peters M, Schultze-Kraft R. (2005). Tropical Forages. Extension Circular 551 (revised). North Dakota State CSIRO, DPI&F(Qld), CIAT and ILRI, Brisbane, Australia. University Extension Service. Fargo, North Dakota. 2. Cole RJ, Dorner JW, Lansden JA, Cox RH, Pape C, 13. Giordano A, Cogan NO, Kaur S, Drayton M, Mouradov Cunfer B, Nicholson SS, Bedell DM. (1977). Paspalum A, Panter S, Schrauf GE, Mason JG, Spangenberg staggers: isolation and identification of tremorgenic GC. (2014). Gene discovery and molecular marker metabolites from sclerotia of Claviceps paspali. J Ag- development based on high-throughput transcript ric Food Chem 25: 1197–1201. sequencing of Paspalum dilatatum Poir. PLOS ONE, 3. National Center for Biotechnology Information (2021). 9(2), e85050. PubChem Compound Summary for CID 9867531,

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