Plant-Parasitic Nematodes Are Potential Pathogens ofMiscanthus×giganteusandPanicum virgatumUsed for Biofuels

Abstract

A survey of Miscanthus × giganteus and switchgrass plots throughout the midwestern and southeastern United States was conducted to determine the occurrence and distribution of plant-parasitic nematodes associated with these biofuel crops. During 2008, rhizosphere soil samples were collected from 24 Miscanthus × giganteus and 38 switchgrass plots in South Dakota, Iowa, and Illinois. Additional samples were collected from 11 Miscanthus × giganteus and 10 switchgrass plots in Illinois, Kentucky, Georgia, and Tennessee the following year. The 11 dominant genera recovered from the samples were Pratylenchus, Helicotylenchus, Xiphinema, Longidorus, Heterodera, Hoplolaimus, Tylenchorhynchus, Criconemella, Paratrichodorus, Hemicriconemoides, and Paratylenchus. Populations of Helicotylenchus, Xiphinema, and Pratylenchus were common and recorded in 90.5, 83.8, and 91.9% of the soil samples from Miscanthus × giganteus, respectively, and in 91.6, 75, and 83.3% of the soil samples from switchgrass, respectively. Prominence value (PV) (PV = population density × √frequency of occurrence/10) was calculated for the nematodes identified. Helicotylenchus had the highest PV (PV = 384) and was followed by Xiphinema (PV = 152) and Pratylenchus (PV = 72). Several of the nematode species associated with the two biofuels crops were plant parasites. Of these, Pratylenchus penetrans, P. scribneri, P. crenatus, Helicotylenchus pseudorobustus, Hoplolaimus galeatus, X. americanum, and X. rivesi are potentially the most damaging pests to Miscanthus × giganteus and switchgrass. Due to a lack of information, the damaging population thresholds of plant-parasitic nematodes to Miscanthus × giganteus and switchgrass are currently unknown. However, damage threshold value ranges have been reported for other monocotyledon hosts. If these damage threshold value ranges are any indication of the population densities required to impact Miscanthus × giganteus and switchgrass, then every state surveyed has potential for yield losses due to plant-parasitic nematodes. Specifically, Helicotylenchus, Xiphinema, Pratylenchus, Hoplolaimus, Tylenchorhynchus, Criconemella, and Longidorus spp. were all found to have population densities within or above the threshold value ranges reported for other monocotyledon hosts.

A synthesis of the ecosystem services impact of second generation bioenergy crop production

“…For imported feedstocks such as Miscanthus, associated pest species may no longer be under control of enemies that occur in their natural range, and so pose a threat to both the feedstock and other crops or vegetation that the pest species can exploit [89]. Emerging evidence of a number of parasitic nematodes [90] that could reduce productivity of Miscanthus suggest that our assumption of resistance to pests for 2G feedstocks may be incorrect. As the relatively low inputs of agrochemicals associated with 2nd generation crops are responsible for many of the suggested environmental benefits, these findings could undermine one of the key arguments for 2G feedstock deployment.…”

Miscanthus Genetics and Agronomy for Bioenergy Feedstock

“…In addition, the larvae of armyworms (Spodoptera frugiperda) have been shown to infest plots of Miscanthus × giganteus [98] along with the aphid Rhopalosiphum maidis [99]. In the United States, plant-parasitic nematodes (Helicotylenchus, Xiphinema, Paratylenchus, Hoplolaimus, Tylenchorhynchus, Criconemella, Longidorus, Heterodera, Paratrichodorus, Hemicriconemoides, Pratylenchus) have been identified as potential pathogens in Miscanthus biofuel crops [100].…”

“…Information collected from Thinggard[97], Gottwald and Adam[101], DEFRA[76], Clifton-Brown et al[76], Prasifka et al[98], Bradshaw et al[99], Mekete et al[100].…”

Biomass Reducing Potential and Prospective Fungicide Control of a New Leaf Blight of Miscanthus × giganteus Caused by Leptosphaerulina chartarum

“…As more and more plots of M.×giganteus and other Miscanthus spp are established for research in different agroecological zones of the world due to the escalating interests in second-generation biofuels, diseases of Miscanthus spp (including M.×giganteus) are beginning to emerge [2,3,5,6,14,23,24]. As this new crop goes into more intensive monoculture systems, it will begin to succumb to the pressure of pathogens that also are continually evolving to find new hosts.…”