Plant Pathology

Our lab integrates the latest technologies to address applied and basic questions in plant pathology , with a goal of helping growers optimize their profits while promoting sustainable agricultural practices.

In The News

Blowing in the Wind: Monitoring and Identifying Fungal Spores

Researcher in the Zeng lab at Southern Piedmont AREC — Priyanka Gangwar, a postdoctoral researcher in the Zeng lab, conducts DNA sequencing using the MinION sequencer. Photo: Yuan Zeng

Zeng Lab - Virginia Tech

Tobacco

Disease Management

Black Shank

Black shank is caused by a fungal pathogen that lives in the soil and attacks tobacco roots and stalks. Widespread continuous planting of flue-cured tobacco cultivars possessing single-gene (designated Ph) resistance to black shank enabled tobacco producers to dramatically reduce the application of soil fungicides beginning in 1996. However, this has led to the breakdown in the efficacy of this resistance by shifting the distribution of the pathogen populations from host race 0 to race 1.

Granville (Bacterial) wilt

Granville (Bacterial) wilt is caused by a soil-inhabiting bacterium invading tobacco plants through one or more roots, often killing the entire plant. The pathogen can also invade tobacco plants through wounds, so early and shallow cultivation and hand-topping can help reduce the spread in infested fields. Although symptoms are somewhat similar to those for black shank, intermediate symptoms of Granville wilt involve wilting on only one side, and wilted leaves may retain their normal green color rather than yellow.

Tobacco Cyst Nematode

Tobacco cyst nematodes (TCN) are microscopic worms that live in the soil and feed on tobacco roots. TCN populations are thought to be decreasing in some fields due to the widespread planting of flue-cured cultivars with the Ph gene. Nematicide tests are conducted annually to evaluate their influence on nematode reproduction and tobacco yield and quality. TCN-resistant cultivars are also evaluated for their potential.

Tobacco Mosaic Virus

The tobacco mosaic virus (TMV) is the most widely distributed virus that affects tobacco crops. TMV can be spread by contaminated clippings mowers in the greenhouse, from tobacco roots and stalks remaining in the soil from previous crops, from weed hosts such as horsenettle and ground cherry, and contaminated objects and surfaces such as trays and sheets, and from manufactured tobacco products. Mosaic-resistant cultivars can reduce damage and may help reduce residual viruses in infested fields. If a TMV-resistant cultivar is planted, the entire field should be planted to the resistant cultivar.

2024 Flue-Cured Tobacco Production Guide