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Management of plant diseases is a subject of concern for researchers as well as growers. Different management practices are being developed and used to combat the rising number of plant pathogens, which threaten nursery crop production. Use of cover crops for sustainable management of soilborne diseases is being explored as an alternative strategy to the chemicals. However, the potential threat of these cover crops acting as a secondary host of these devastating soilborne pathogens has not been described. We studied the response of the major cover crops being used by woody ornamental growers in the Southeastern United States to Phytopythium vexans, Phytophthora nicotianae, and Rhizoctonia solani in greenhouse conditions to identify the effective cover crops that can be used in a nursery field production system. Data related to post-emergence damping-off and plant growth parameters (plant height increase and fresh weight) were recorded. Similarly, cover crop roots were assessed for root rot disease severity using a scale of 0–100% roots affected. Among the tested cover crops, the grass cover crops triticale (×Triticosecale Wittm. ex A. Camus.), annual ryegrass (Lolium multiflorum L.), Japanese millet (Echinochloa esculenta (A. Braun) H. Scholz), and the legumes Austrian winter pea (Pisum sativum var. arvense (L.) Poir) and cowpea ‘Iron and Clay’ (Vigna unguiculata (L.) Walp.), showed lower root rot disease severity and post-emergence damping-off in the soil inoculated with P. nicotianae, R. solani, or P. vexans compared to the other crops. Since these cover crops can act as non-host crops and benefit the main crop in one way or another, they can be used in the production system. Further research is recommended to evaluate their performance in a natural field setting.
Milan Panth; Anthony Witcher; Fulya Baysal-Gurel. Response of Cover Crops to Phytopythium vexans, Phytophthora nicotianae, and Rhizoctonia solani, Major Soilborne Pathogens of Woody Ornamentals. Agriculture 2021, 11, 742 .
AMA StyleMilan Panth, Anthony Witcher, Fulya Baysal-Gurel. Response of Cover Crops to Phytopythium vexans, Phytophthora nicotianae, and Rhizoctonia solani, Major Soilborne Pathogens of Woody Ornamentals. Agriculture. 2021; 11 (8):742.
Chicago/Turabian StyleMilan Panth; Anthony Witcher; Fulya Baysal-Gurel. 2021. "Response of Cover Crops to Phytopythium vexans, Phytophthora nicotianae, and Rhizoctonia solani, Major Soilborne Pathogens of Woody Ornamentals." Agriculture 11, no. 8: 742.
Weed control is critical in cutting propagation to maximize root growth and liner quality, but hand weeding is time consuming and not cost efficient. Pre-emergence herbicides are widely used in container-grown nursery crop production, but concerns of potential phytotoxicity have limited widespread use in propagation. Mulches are a viable alternative for weed control but few products have been evaluated in propagation. Five pre-emergence herbicides and five mulches were evaluated for rooting stem cuttings of three nursery crop species and for control of four weed species. Mulches were applied (0.8 cm depth) prior to sticking cuttings while pre-emergence herbicides were applied (low labeled rate) two weeks after sticking cuttings. Rooting percentage, root dry weight, and shoot dry weight were not affected by pre-emergence herbicide or mulch, except for butterfly bush (Buddleja davidii ‘Nanho Blue’) which was severely injured when treated with the pre-emergence herbicide isoxaben. Oxyfluorfen + oxadiazon provided excellent control of all tested weed species and has potential to be used in propagation of a number of crops. Mulches did not provide adequate weed control, but increased application depth may enhance efficacy and should be further evaluated.
Anthony L. Witcher; Isha Poudel. Pre-Emergence Herbicides and Mulches for Weed Control in Cutting Propagation. Agronomy 2020, 10, 1249 .
AMA StyleAnthony L. Witcher, Isha Poudel. Pre-Emergence Herbicides and Mulches for Weed Control in Cutting Propagation. Agronomy. 2020; 10 (9):1249.
Chicago/Turabian StyleAnthony L. Witcher; Isha Poudel. 2020. "Pre-Emergence Herbicides and Mulches for Weed Control in Cutting Propagation." Agronomy 10, no. 9: 1249.
Diseases caused by soilborne pathogens are a major limitation to field grown nursery production. The application of cover crops for soilborne disease management has not been widely investigated in a woody ornamental nursery production system. The objective of this study was to explore the impact of winter cover crops usage on soilborne disease management in that system. Soils from established field plots of red maple (Acer rubrum L.) with and without winter cover crops (crimson clover (Trifolium incarnatum L.) or triticale (× Triticosecale W.)) were sampled following the senescence of the cover crops. Separate bioassays were performed using red maple cuttings on inoculated (with Phytopythium vexans, Phytophthora nicotianae or Rhizoctonia solani) and non-inoculated field soils. The results indicated that winter cover crop usage was helpful for inducing soil disease suppressiveness. There was lower disease severity and pathogen recovery when the cover crops were used compare to the non-cover cropped soil. However, there were no differences in maple plant fresh weight and root weight between the treatments. The rhizosphere pseudomonad microbial population was also greater when the cover crops were used. Similarly, the C:N ratio of the soil was improved with the cover crop usage. Thus, in addition to improving soil structure and reducing erosion, cover crops can provide improved management of soilborne diseases. Therefore, stakeholders can consider cover crop usage as an alternative sustainable management tool against soilborne diseases in field nursery production system.
Milan Panth; Fulya Baysal-Gurel; Terri Simmons; Karla M. Addesso; Anthony Witcher. Impact of Winter Cover Crop Usage in Soilborne Disease Suppressiveness in Woody Ornamental Production System. Agronomy 2020, 10, 995 .
AMA StyleMilan Panth, Fulya Baysal-Gurel, Terri Simmons, Karla M. Addesso, Anthony Witcher. Impact of Winter Cover Crop Usage in Soilborne Disease Suppressiveness in Woody Ornamental Production System. Agronomy. 2020; 10 (7):995.
Chicago/Turabian StyleMilan Panth; Fulya Baysal-Gurel; Terri Simmons; Karla M. Addesso; Anthony Witcher. 2020. "Impact of Winter Cover Crop Usage in Soilborne Disease Suppressiveness in Woody Ornamental Production System." Agronomy 10, no. 7: 995.
Root zone temperature (RZT) in nursery containers commonly exceeds ambient temperature during the growing season, negatively impacting crop growth and quality. Black nursery containers absorb radiant heat resulting in excessive RZT, yet other types of containers and different substrates can moderate RZT. We conducted studies in Tennessee and Alabama to evaluate the effects of container type and substrate on RZT and growth of ‘Green Giant’ arborvitae (Thuja standishii × plicata ‘Green Giant’). Trade gallon arborvitae were transplanted into black, white, or air pruning containers filled with pine bark (PB) or 4 PB: 1 peatmoss (v:v) (PB:PM). Plants grown in PB:PM were larger and had greater shoot and root biomass than plants grown in PB, likely due to increased volumetric water content. Plant growth response to container type varied by location, but white containers with PB:PM produced larger plants and greater biomass compared with the other container types. Root zone temperature was greatest in black containers and remained above 38 °C and 46 °C for 15% and 17% longer than white and air pruning containers, respectively. Utilizing light color containers in combination with substrates containing peatmoss can reduce RZT and increase substrate moisture content thus improving crop growth and quality.
Anthony L. Witcher; Jeremy M. Pickens; Eugene K. Blythe. Container Type and Substrate Affect Root Zone Temperature and Growth of ‘Green Giant’ Arborvitae. Horticulturae 2020, 6, 22 .
AMA StyleAnthony L. Witcher, Jeremy M. Pickens, Eugene K. Blythe. Container Type and Substrate Affect Root Zone Temperature and Growth of ‘Green Giant’ Arborvitae. Horticulturae. 2020; 6 (2):22.
Chicago/Turabian StyleAnthony L. Witcher; Jeremy M. Pickens; Eugene K. Blythe. 2020. "Container Type and Substrate Affect Root Zone Temperature and Growth of ‘Green Giant’ Arborvitae." Horticulturae 6, no. 2: 22.
Container-grown nursery crops are commonly exposed to root zone stress due to inadequate moisture and supraoptimal root zone temperature (RZT). Compost substrates can improve water and nutrient retention but plant responses can vary due to physical and chemical properties. Dark color containers absorb solar radiation through the container side wall leading to excessive heat buildup in the substrate, yet white containers can reduce RZT. Compost substrates and container color were examined for effects on RZT and growth of “Green Giant” arborvitae (Thuja standishii × plicata “Green Giant”). “Green Giant” arborvitae were transplanted into white or black containers (11.3 L) filled with a pine bark substrate (PB) or PB mixed with compost (C) at two different proportions [PB:C (9:1) and PB:C (7:3)]. White containers reduced maximum RZT by up to 7 °C and RZT remained above 38 °C for only 3% of the time compared to 21% of the time in black containers. Shoot growth increased over 50% in white containers compared to black containers. Compost increased substrate volumetric water content (VWC), increased shoot growth by up to 24%, and reduced total irrigation volume by up to 40%. Utilizing white containers for minimizing RZT and compost-amended substrates to maintain adequate VWC can improve root and shoot growth and overall crop quality while reducing nursery production inputs.
Anthony L. Witcher; Jeremy M. Pickens; Eugene K. Blythe. Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae. Agronomy 2020, 10, 484 .
AMA StyleAnthony L. Witcher, Jeremy M. Pickens, Eugene K. Blythe. Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae. Agronomy. 2020; 10 (4):484.
Chicago/Turabian StyleAnthony L. Witcher; Jeremy M. Pickens; Eugene K. Blythe. 2020. "Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae." Agronomy 10, no. 4: 484.
Flowering dogwood (Cornus florida) is a valuable nursery product typically produced as a field-grown crop. Container-grown flowering dogwood can grow much faster than field-grown plants, thus shortening the production cycle, yet unacceptable crop loss and reduced quality continue to be major issues with container-grown plants. The objective of this research was to evaluate the effects of container size and shade duration on growth of flowering dogwood cultivars Cherokee Brave™ and Cherokee Princess from bare-root liners. In 2015, bare-root liners were transplanted to 23-L (no. 7) containers and placed under shade for 0 months (full sun), 2 months (sun4/shade2), 4 months (sun2/shade4), or 6 months (full shade) during the growing season. In 2016, one-half of the plants remained in no. 7 containers and the other half were transplanted to 50-L (no. 15) containers and assigned to the same four shade treatments. In 2015, plant height was greatest with full shade for both cultivars, whereas stem diameter and shoot dry weight (SDW) were greatest in full shade for Cherokee Brave™. In 2016, both cultivars in no. 15 containers had greater plant height, stem diameter, root dry weight (RDW), and SDW. Full shade resulted in the greatest height, stem diameter, RDW, and SDW for Cherokee Brave™, and improved overall growth for ‘Cherokee Princess’. However, vigorous growth due to container size and shade exposure increased the severity of powdery mildew (Erysiphe pulchra) in both years. Substrate leachate nutrient concentration (nitrate nitrogen and phosphate) was greater in no. 15 containers but shade duration had no effect.
Anthony L. Witcher; Fulya Baysal-Gurel; Eugene K. Blythe; Donna C. Fare. Container Size and Shade Duration Affect Growth of Flowering Dogwood. HortTechnology 2019, 29, 842 -853.
AMA StyleAnthony L. Witcher, Fulya Baysal-Gurel, Eugene K. Blythe, Donna C. Fare. Container Size and Shade Duration Affect Growth of Flowering Dogwood. HortTechnology. 2019; 29 (6):842-853.
Chicago/Turabian StyleAnthony L. Witcher; Fulya Baysal-Gurel; Eugene K. Blythe; Donna C. Fare. 2019. "Container Size and Shade Duration Affect Growth of Flowering Dogwood." HortTechnology 29, no. 6: 842-853.