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Growers Briefed on Pepper Production Challenges

The Tomato Magazine
January 2007

There was everything you ever wanted to learn about pepper production and more at the 2006 Great Lakes Fruit, Vegetable & Farm Market Expo pepper
session. The presentations took place Dec. 5 at the DeVos Place Convention Center in Grand Rapids, Mich. Topics covered included:

• “Damping-off of Pepper Transplants,” by Sally Ann Miller, a plant pathologist at The Ohio State University, Wooster, Ohio.
• “Pepper IPM in New England,” by Jude Boucher, a researcher with the University of Connecticut Cooperative Extension System, Vernon, Conn.
• “Phytophthora Research Update in Peppers,” by Mary Hausbeck, a plant pathologist at MSU.
• “Spacing Studies in Peppers,” a second presentation by OSU’s Sally Miller.

Damping-off Disease Research
In greenhouse environments, damping-off, a disease caused by Rhizoctonia solani and Pythium spp., can cause significant losses for transplant production,
Sally Miller told the group. Damping-off is associated with plant crowding, variable temperatures, over-watering, high humidity and the lack of fungicides highly effective against damping-off pathogens.

“We evaluated a number of products and tactics to suppress these pathogens and reduce the incidence of Rhizoctonia and Pythium damping-off in pepper
transplants,” Miller reported. “Pepper is particularly susceptible to damping-off during seedling production.”

Among the treatments used were: composted cow manure (4 percent total nitrogen), Omega Grow Plus, Moncut, Endorse, Serenade and Thiram. Endorse
and Serenade were used at different rates.

“All of the treatments, except the low rate of Endorse and all rates of Serenade, significantly reduced Rhizoctonia damping-off of pepper seedling,” Miller
said. “In the non-inoculated control, only 1.6 percent of seedlings damped-off.

Composted cow manure or T. hamatum 382 incorporated into the planting mix, and the standard Thiram seed treatment were most effective, resulting in the highest number of healthy seedlings. However, neither the compost nor the T. hamatum 382 treatment was signifi cantly more effective than the Thiram treatment.”

Omega Grow Plus, Moncut and the 2.0 lb/100 gal rate of Endorse were significantly less effective than the best treatment, amendment of the planting mix with composted cow manure, she added. Serenade ASO drench was not effective in reducing Rhizoctonia damping-off, and the higher rates (1 and 2 percent) of
Serenade appeared to be phototoxic to pepper seed.

“Pre-emergence damping-off caused by P. aphanidermatum was very high in this study (70.3 percent),” Miller reported.“Ranman, composted cow manure, Omega Grow, T. hamatum 382 and the standard Thiram seed treatment significantly decreased Pythium damping-off of pepper seedlings. Ranman was the most effective treatment; Ranman, composted cow manure and Omega Grow treatments were signifi cantly more effective in reducing Pythium damping-off than the standard Thiram seed treatment. Serenade ASO drench, Seacide, Phosphonate, Prestop, Omega Grow Plus, Mycostop and two fluorescent Pseudomonads did not reduce damping-off compared to the untreated, inoculated control.”

In conclusion, Miller pointed out that incorporation of 10 percent composted cow manure in potting mix was consistently effective in reducing damping-off in peppers. This particular treatment also resulted in taller, healthier plants than other treatments or the controls.

“Compost amendments increase the organic matter content of planting mixes and also provide additional nutrients which may contribute to better germination and the production of healthier seedlings,” the researcher said.

In this experiment, T. hamatum 382 was relatively more effective in reducing Rhizoctonia than Phythium damping-off, she said. Ranman was the most effective
treatment against Pythium damping-off but is not yet registered for use against the disease.

Prioritizing IPM Options
The key to prioritizing possible IPM options in peppers is to realize that there are only five or six major pepper pests that must be dealt with annually, noted
Jude Boucher in his presentation entitled “ Pepper IPM in New England.” These are: weeds, Phytophthora blight, bacterial leaf spot, pepper maggot, European corn borer and aphids.

There also are several dozen minor or occasional pests, he added, but rarely do growers have to deal with more than one or two of these during a particular year.

“The most successful growers design their pest management plan around the chronic (usually the major) problems and implement the solutions as part of their
standard operating procedure,” Boucher said.

Phytophthora Research Reported
In her presentation on Phytophthora research in Michigan, Mary Hausbeck noted that the fungus involved, Pytophthora capsici, is favored by rain and warm temperatures that occur during the Michigan growing season and has recently been found in irrigation ponds and other surface water sources.

“The most effective control measures are to avoid planting in infested soil and limit the spread of the pathogen to clean fields,” she warned. “Crop rotation is difficult as infested acreage and urban pressure is increasing across the major growing areas of the state.”

The use of properly constructed raised beds can be helpful, Hausbeck added. Such beds keep vulnerable plants from saturated soil conditions. Foliar application of preventive fungicides can be effective if proper coverage and timing of applications can be achieved. Certain fumigants are also available that can help lower crop losses.

“A combined approach of all available control techniques is more effective than using just one control measure,” the researcher said. Hausbeck reported the results of a 2006 study that looked at one registered fungicide and several new products and their efficacy in controlling Phytophthora.

In her fungicide trial, only plants treated with IR6141 50WP 0.21 lb + Remedier 4WP 2.2 lb and V-10162 5.73FL 1l75 pt had significantly less plant death than the untreated control, she told the group. Only V-10162 5.73FL 1.75 pt had significantly higher yield than the untreated control.

In her cultivar trial, 11 different cultivars were planted in a fi eld located near Fremont, Mich. None of the plants in the trial died as a result of the disease.
However, all had some level of a silvering defect due to a separation of the outer cuticle from the fruit.

The cultivar, Red Knight, had over 25 percent affected fruit, the researcher pointed out, and was blemished enough to be unmarketable. Alliance, a P. capsici
tolerant cultivar, was least affected by the defect and all of the fruit harvested were marketable. The cultivars Camelot, Aristotle and the germplasm line C85XC86 had defect levels below 10 percent. There were no signifi cant differences in yields.

Impact of Pepper Plant Spacing
In her second presentation of the day, Sally Miller reported on her studies examining spacing in peppers.

“Bell pepper fruit yield increased proportionally with plant stand density in the trial conducted at the OSU-OARDC NCARS,” Miller told the group. “Weight
per bell pepper red fruit was lower at the highest than at the middle or lowest stand densities at the research station, but remained unaffected at tested stand densities on commercial farms. Most other workers have reported that bell pepper fruit size or quality is not affected by stand density.”

On commercial bell pepper farms, Miller noted that the relationship between fruit yield and plant stand density was not clearly determined, but on the commercial jalapeño farm, greater yield was obtained at the higher stand density.

“A broader range of stand densities evaluated on commercial farms should have resulted in more pronounced yield differences,” she said. “In banana peppers,
stand density did not infl uence weight per fruit.”

© 2007 Columbia Publishing

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