ABSTRACT
Ginger (Zingiber officinale Roscoe) is one of the most widely consumed medicinal herb in the world, and the U.S. imports of ginger have risen in recent years because of its health benefits. Seed rhizome and soilborne diseases are serious concerns of ginger worldwide (Stirling 2004; Moreira et al. 2013), including the recent observations of Fusarium yellows and rhizome rot in the Commonwealth of Virginia. In October 2018 and 2019, ginger plants with yellowing of leaf margins and stunted growth were uprooted from a 9.1 m × 14.6 m high tunnel (HT) and from an outdoor raised bed at Virginia State University's Randolph farm. Disease incidence in the HT and the raised bed was estimated between 5-70%. Small pieces (2-5 mm) of symptomatic rhizomes were disinfected with 0.6% sodium hypochlorite solution and placed on potato dextrose agar (PDA) Petri plates to recover fungal isolates. Hyphal tips from these isolates were transferred to fresh PDA to obtain pure cultures. The fungal colonies were pinkish-white initially, and turned purplish-pink after 5-7 days of incubation at 25 °C. The microconidia were aseptate, oval or elliptical, hyaline, and measured 5 to 12 × 4 to 6 µm in size. Macroconidia were with 3 to 5 septations, curved like a sickle towards the ventral side, hyaline, smooth and thin-walled, and 15 to 40 × 3 to 6 µm in size. Fungal genomic DNA of one isolate (Gf-VA-3) was extracted from a 7-days old culture using PrepMan®Ultra (Thermo Fischer Scientific, Cheshire UK). Four conserved regions of the isolated pathogen, internal transcribed spacer (ITS), translation elongation factor (EF), ß-tubulin (Bt), and calmodulin (cal) gene regions were amplified using ITS1 and ITS4 (White et al. 1990), ef1α and ef2α (O'Donnell et al. 1998), Bt2a and Bt2b (Glass and Donaldson 1995), and calA1 and calQ1 (Carbone and Kohn 1999), respectively. PCR products were sequenced, and amplicons deposited in GenBank with accession numbers MT337417 for ITS, MT436712 for Bt, MT802441 for cal and MW816632 for EF. A 99-100% identity with Fusarium oxysporum was matched with accession nos. MW776326 for ITS, MN646766 for the ß-tubulin, MT010904 for the calmodulin and MN258350 for the translation elongation factor genes. For pathogenicity test, six 6-week-old healthy ginger plants grown on sterilized potting mix in the greenhouse were inoculated by injecting 3-ml of a 1 × 108 micro- and macro-conidia suspension per ml at the crown area transcending to the rhizome. Another set of six plants were injected with distilled and autoclaved water in the same way. After four weeks, leaves withered, plants exhibited yellowing and wilt followed by stunted growth and eventually complete collapse of the six inoculated plants, however control plants showed none of the symptoms. The same pathogen was re-isolated from the inoculated plants. The pathogenicity test was repeated, and the same results were observed. Fusarium yellows and rhizome rot has been reported from Hawaii in the U.S. (Trujillo 1963), Brazil (Moreira et al. 2013), Australia (Stirling 2004), China (Li et al. 2014), and India (Shanmugam et al. 2013). To our knowledge, this is the first report of Fusarium yellows and rhizome rot on ginger in the Continental U.S. The disease is seed rhizome and soilborne leading to poor establishment and hence economic loss in ginger production.
ABSTRACT
The soybean crop is one of the most important crops worldwide, as the seeds are used for both protein meal and vegetable oil. Soybean acreage covers an estimated 6% of the arable land in the world, and since the 1970s, soybean has had the highest percent increase of hectares in production compared to any other major crop. As demand for soybean continues to rise, the production area and worldwide trade are likely to increase. Biotic constraints, such as pathogens, pests, and weeds, can be detrimental to soybean production, causing significant negative impacts to yield. To successfully reduce losses caused by pathogens and pests, various practices such as cultural and seed sanitation techniques, pesticide applications, and deployment of resistance are used. For many years, public institutions have conducted regional yield trials on both private and public sector soybean cultivars. In Illinois, the University of Illinois Variety Testing Program created a public database for growers. Prompted in part by disease reports on cultivars entered into the Variety Testing Program, the Illinois Soybean Association began providing funds in 1998 to obtain additional information from regional trials to benefit growers in the state. The researchers in the Soybean Variety Testing Program conduct replicated field trials and evaluate these plots for agronomic characteristics such as height, lodging, maturity, and yield. In addition to standard yield trial data, protein and oil content are analyzed.