Sugar Producer

18 Sugar Producer JANUARY 2021 The sugarbeet cyst nematode Heterodera schachtii is a significant pathogen of sugarbeets worldwide. It infects more than 200 different plants, including many important cole crop vegetables, often causing considerable economic loss. California's only remaining sugarbeet factory is located in the town of Brawley in the Imperial Valley, close to the Mexican border. The area's low desert climate is characterized by hot summers and mild, sunny winters. When the Holly Sugar Corporation opened its factory in 1947, the surrounding farmland was free of H. schachtii. However, the nematode was quickly introduced, most likely with contaminated seed or machinery from other sugarbeet-growing areas along the California coast, where beets had been grown the late 1870s. Today, sugarbeet production in California is limited to about 25,000 acres in the Imperial Valley. The crop is seeded in fall and harvested from April to early August, and, despite the nematode's widespread presence, the growers produce the highest gross sugar yields per acre in the U.S. Since the 1960s, the primary strategy Imperial Valley growers have employed to mitigate yield reduction due to H. schachtii has involved monitoring the level of cyst infestation at harvest. When the number of H. schachtii cysts exceeds an economically damaging threshold, growers are contractually required by the local sugar factory to either crop that field for three to five years with plants that do not support the nematode's reproduction or to leave it fallow. The natural population decline is approximately 50 percent per year, mainly due to the nematodes hatching when no host plant is present and microbial parasitism. One of the microorganisms responsible for the population reduction is a soil fungus that consumes nematode females and eggs. This fungus, Hyalorbilia aff. multiguttulata (formerly Dactylella oviparasitica) was initially shown by nematologists and plant pathologists from the University of California, Riverside (UCR) to cause long-term suppression of sugarbeet cyst nematode populations in a field at the university's agricultural operations near Riverside. Other scientists detected closely related fungal species in Arkansas UNDERGROUND UNDERGROUND Ally Ally Natural fungal protection against sugarbeet cyst nematodes By J. Ole Becker and James Borneman Departments of Nematology, Microbiology and Plant Pathology University of California, Riverside Harvested sugarbeets on their way into the processing facility in Brawley, Calif. © 2020 Paul Ruegger Young, white female Heterodera schachtii on host roots. © 2017 J. Ole Becker Hyalorbilia fungus destroying a young sugarbeet cyst nematode egg. © 2017 J. Ole Becker

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