Anaerobic soil disinfestation (ASD) is a promising alternative to chemical fumigation to control soil-borne plant pathogens and weeds. This research focused on evaluating several locally available carbon sources for ASD on weed control, evaluating the performance of brewers' spent grain (a promising carbon source) under field conditions, and evaluating whether yeast addition enhanced the effectiveness of ASD treatments. A series of greenhouse trials were conducted at the Southern Piedmont AREC (Agricultural Research and Extension Center). The greenhouse trials were conducted in PVC tubes, 20 cm tall and 15 cm in diameter. The first set of trials evaluated ASD conducted over 21-day periods of ASD using locally available carbon sources. The carbon sources included brewer`s spent grain, buckwheat (Fagopyrum esculentum), cowpea (Vigna unguiculata), paper mulch, peanut (Arachis hypogaea) shells, rice bran, sorghum-sudangrass (Sorghum drummondii), and waste coffee grounds applied at 4 mg of C/g of soil. The targeted weed species included common chickweed (Stellaria media (L.) Vill.), redroot pigweed (Amaranthus retroflexus L.), white clover (Trifolium repens L.), and yellow nutsedge (Cyperus esculentus L.). All ASD treatments significantly reduced weed viability compared to the non-treated control. The yeast amendments enhanced weed control over ASD without yeast. The second set of greenhouse trials was focused on ASD using brewer`s spent grain, and on evaluating ASD at the half and one-third carbon dose rates. The target pests were the same weed species in the first set of trials, and Pythium irregulare was added as an additional target pest. This set of trials indicated yeast enhanced addition the effect of BSG in ASD on both weeds and P. irregulare, indicating the potential to reduce carbon input necessary for effective ASD. A follow-up, two seasons, open-field trial conducted over two growing seasons at the Hampton Roads AREC focused on understanding the effects of ASD on weed density and strawberry fruit yield and fruit quality in annual hill strawberry production. The treatments included ASD at standard or half carbon dose rates, with or without yeast. Fumigation (80% chloropicrin + 20% 1,3-dichloropropene) and non-treated plots were used as control groups. Weed suppression with ASD was consistent for most of the broadleaf weed species, and total weed counts were significantly reduced compared to non-treated controls. Yield from ASD with yeast was higher than ASD without yeast and non-treated control in one growing season, while the increase in yield did not occur in another growing season. Yeast may have potentially enhanced the yield effects of ASD but lacked consistency. Yeast may have the potential to enhance ASD effectiveness. / Doctor of Philosophy / Strawberry is a high-value crop known for its brightly colored, sweet tasting, juicy and fleshy fruit that possesses a unique aroma. The southern region is the second large region of strawberry production in the United States. Strawberry is susceptible to soil-borne pests, including weeds and diseases. Preplant control of soil-borne diseases and weeds is important for strawberry production. Early season weeds can compete with newly transplanted strawberry plugs for nutrients, light, and other resources. However, currently, the limited options of pre-plant chemical fumigants and herbicides available in strawberry plasticulture make weed control a challenge in strawberry production. Anaerobic soil disinfestation (ASD) may be an effective alternative to preplant chemical fumigation. Anaerobic soil disinfestation involves three steps- applying carbon sources to the soil, covering the bed with black tarp, and watering the soil to maintain certain soil moisture to field capacity generally for 21 days.
However, there are only a few studies on weed control using ASD in the southern region; locally available carbon sources also need to be evaluated. Thus, this study focused on evaluating several locally available carbon sources (cover crops, brewer`s spent grain, used coffee ground, paper mulch, peanut shell) for ASD to control troublesome weeds (common chickweed, redroot pigweed, white clover, yellow nutsedge). This study also explored a new method that involves mixing distiller's yeast with solid carbon sources in order to enhance the ASD weed control effect. Additionally, this study evaluated the effect of ASD using reduced carbon inputs, potentially reducing the total cost of ASD by reducing the carbon input. A series of greenhouse studies were conducted at the Southern Piedmont Agricultural Research and Extension Center (AREC), Blackstone, VA, with a follow-up field study done at the Hampton Roads AREC. The greenhouse trials evaluated carbon sources including brewer`s spent grain, buckwheat, cowpea, paper mulch, peanut shells, rice bran, sorghum-sudangrass, and waste coffee grounds. These greenhouse experiments were conducted in containers made from PVC tubes, and strawberry plants were not involved. The main objective of the greenhouse trial was to test the suppression of four troublesome weeds, including common chickweed, redroot pigweed, yellow nutsedge, and white clover. The most effective treatments in the greenhouse studies were further investigated in the field trial. The brewer`s spent grain was again used in the field trial, and treatments included ASD using a full or half dose of brewer's spent grain, with or without yeast. We evaluated the effects of these treatments on weed control, plant crop growth, and crop yields. Fruit quality factors, including fruit firmness, sweetness, and size, were also evaluated.
In summary, all of the carbon sources evaluated provide similar weed control. Adding yeast showed potential to enhance the effect of ASD using brewer`s spent grain. Adding yeast also increased the effectiveness of the half-rate of the carbon source, showing the potential for effective pre-plant pest control for strawberry using ASD treatments with significantly reduced C dose rates.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/112096 |
| Date | 14 April 2021 |
| Creators | Liu, Danyang |
| Contributors | Horticulture, Samtani, Jayesh Bharat, Derr, Jeffrey F., Johnson, Charles S., Butler, David |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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