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- Author or Editor: E. Barclay Poling x
In recent years, anthracnose fruit rot (AFR) caused by Colletotrichum acutatum J.H. Simmonds, has become an even more serious threat to strawberry plant and fruit producers in major strawberry-growing areas of North America. This highly virulent pathogen causes fruit rot, crown rot, root rot, and lesions on petioles and stolons. In fruit-production fields, the best way to control AFR is to prevent the introduction of the pathogen into the field by using anthracnose-free transplants. A critical step in controlling the disease then, lies in effective nursery management practices. Participants in this workshop outlined several key management strategies, including methods to eliminate pathogen inoculum, cultural practices that reduce host plant susceptibility, and chemical and biological control measures. Industry members stressed the importance of giving research priority to developing improved methods of nursery field sampling and detection of C. acutatum in asymptomatic plants with latent infection. Being able to rapidly and economically diagnose C. acutatum in symptomless plant material at each step in the multiyear nursery plant propagation cycle (foundation, registered, and certified plants), will help nursery growers minimize the potential of selling C. acutatum-infected transplants to fruit growers. A video recording of the 4-h workshop was produced by ASHS Video Workshop Series (http://ashs.org/resources/videoworkshopseries.html).
Active frost protection methods may be expensive, but a correctly selected and operated system can provide more consistent crops and improved cash flow in years of potentially damaging cold events at postbudbreak stages of grape development. The selection of an active frost protection system depends on a number of factors, including the prevailing climatic conditions that occur during the spring season at the vineyard location, the costs associated with different frost control systems as well as considerations related to the reliability and relative simplicity of operating the equipment associated with each method. In winegrape production areas in North Carolina, hoar (white) frosts are the predominant cold threat in the postbudbreak period. A wind machine can be a very cost-effective investment on sites that are prone to a damaging frost event in 1 of 5 years or with a higher frequency of occurrence. However, wind machines have less overall usefulness in growing areas where there is also potential for black frosts (a more damaging radiational event than a hoar frost) and frosts/freezes (events with subfreezing temperatures and winds in the range of 2.2 to 4.5 m·s−1). For black frost events, a well-designed overvine sprinkling system can provide nearly 6 °C protection; sprinkling is also an appropriate management option for frost/freeze events. Windborne freezes are far less common at the postbudbreak stages but represent the most damaging type of cold event that can occur in eastern and midwestern winegrape regions in the United States. Methods that reliably delay budbreak (e.g., dormant oils, evaporative cooling with targeted sprinklers) may represent the best near-term opportunity for growers to decrease or avoid vine injury from freeze events such as the early April Easter freeze of 2007 that devastated grape vineyards through much of the midwest and southeastern United States.
In the article “Comparison of Three Methods for Determining the Floral or Vegetative Status of Strawberry Plants” by Edward F. Dumer and E. Barclay Poling [Journal 110(6):808–811, Nov. 1985], the Fig. 2 caption was incorrect. The correct caption should read: Representative central longitudinal section of A. Questionable meristem (bar = 10 μ), B. Vegetative apex (bar = 10 μ), and C. Reproductive meristems (bar = 20 μ).
Three methods for determining the vegetative or floral status of the cultivated strawberry (Fragaria × ananassa Duch.) were compared. Dissection under a stereoscope was the most reliable method, followed by macroscopic evaluation of flower cluster development under long days. Macroscopic flower cluster production was highly dependent on the amount of natural chilling received by the plants prior to being placed under long day conditions, and differed among cultivars. Central longitudinal microtomed sections of apical meristems were unreliable due to their subjective nature. The time of flower bud initiation also was estimated. ‘Allstar’, ‘Earliglow’, and ‘Tribute’ initiated flower buds in late September; ‘Apollo’ and ‘Sequoia’ in early October; and ‘Titan’ in mid-October.
This study estimates and compares the production costs and profitability of muscadine grape (Vitis rotundifilia) production under the single-wire (SW) and the Geneva double curtain (GDC) trellis systems with and without drip irrigation. Profitability analysis revealed that muscadine grape production can be a profitable venture. Irrigated muscadine grape vineyards were shown to be more profitable than nonirrigated vineyards. The comparison of the GDC trellis system and the SW trellis system indicates that the GDC trellis system is more profitable. Returns to land and management from muscadine grapes grown under the GDC system were found to be less sensitive to changes in prices and yields than the returns from muscadine grapes grown under the SW trellis system. Net returns from irrigated systems were also found to be less sensitive to variations in prices and yields than nonirrigated systems. The estimated total costs of establishing (Years 0–3) a muscadine grape vineyard were between $9783/acre and $15,065/acre depending on the production system used. For the GDC production system, which was the most profitable production system, the estimated return to land and management was $447/acre. Cash flow analysis demonstrated that the payback period for this system can be achieved in the 10th year, whereas the net present value of the investment was estimated at $4484 and the internal rate of return was estimated at 9.6%.
‘Douglas’, ‘Tufts’, and ‘Pajaro’ strawberry (Fragaria × ananassa Duch.) plants were sampled for 3 consecutive years (1982–1984), and ‘Chandler’ plants were sampled for one year (1984) from September through October from a North Carolina nursery. Plants were subjected to short days (12-hr photoperiod) at day/night temperatures of 15.5°/4.4°C in 1982–1983 and to short days (9-hr photoperiod) and long days (9-hr photoperiod with a 3-hr night interruption) with or without chilling [15.5°/4.4° (day/night) or 22.0718.0° (day/night), respectively] in 1984 for 0, 1, 6, or 12 days in the NCSU phytotron. After treatment, plants were shipped to Florida for planting in the winter planting system for evaluation of early season yield (1 Dec. -15 Jan.). Optimum digging dates for all cultivars were observed to be a photoperiod response. Chilling enhanced early yield for ‘Douglas’ and ‘Pajaro’ when plants were dug prior to or at the optimum date. Plants dug later than the optimum date had much lower yields, even with substantial chilling. In ‘Chandler’, slight chilling (<125 hr from 1 Sept. until digging date) suppressed early yield, while increased chilling (>125 hr) enhanced early yield when plants were dug at or prior to the optimum date. Chilling decreased early yield in ‘Tufts’ regardless of digging date. Significant yield increases were only obtained with chilling much greater than that which naturally occurs in North Carolina.
Plugs are rapidly replacing fresh-dug bare-root and cold-stored frigo plants as transplants for strawberry (Fragaria × ananassa) production worldwide. Plugs have many advantages over these other types of propagules. They are grown in controlled environments (greenhouses, tunnels) in less time than field produced bare-root transplants, and are not exposed to soilborne pathogens. Plugs afford greater grower control of transplanting dates, provide mechanical transplanting opportunities and allow improved water management for transplant establishment relative to fresh bare-root plants. New uses for plugs have been identified in recent years; for example, photoperiod and temperature conditioned plugs flower and fruit earlier than traditional transplants and plugs have been used for programmed greenhouse production. Tray plants have superior cold storage characteristics relative to bare-root, waiting-bed transplants. Both fresh and frozen plugs are used in a number of indoor and outdoor growing conditions and cultural systems.
The costs associated with growing, harvesting and marketing strawberries (Fragaria × ananassa) using the plasticulture production system were estimated to be $13,540/acre ($33,457/ha). Net revenue analysis showed that growers would have to charge at least $0.85 and $1.40/lb ($1.87 to $3.09/kg) for pick-your-own (PYO) and prepicked fruit, respectively, and sell 12,000 lb of berries per acre (13,449.9 kg·ha-1) to cover this expense. Break-even analysis indicated that growers would have to charge a PYO price of $0.65/lb ($1.43/kg) and $1.20/lb ($2.64/kg) for prepick berries and sell a minimum of 15,041 lb/acre (16,858.4 kg·ha-1) to cover the projected expenses. However, if a grower received $0.95 and $1.50/lb ($2.09 and $3.31/kg) for the PYO and prepicked fruit, respectively, he/she would only have to sell 10,622 lb of berries per acre (11,905.4 kg·ha-1) to break even. It was assumed that an average of 11.6 lb (5.26 kg) of fruit would be sold to PYO customers and an average of 7.1 lb (3.22 kg) would be sold to customers who visited the fruit stand. Under these assumptions, the breakeven yield of 14,724 lb/acre translates into a requirement to sell fruit to at least 1,539 customers per acre (3,802.8 customers/ha) at the lowest combination of prices while a yield of 10,398 lb/acre converts to a minimum of 1,087 customers per acre (2,685.9 customers/ha) at the higher prices. Customers were also surveyed at direct market operations in Spring 1999 to gain insight into consumer demographic characteristics, why customers select a specific PYO or prepick direct market strawberry outlet, average expenditures per customer, typical driving distances to direct market strawberry operations, and the effectiveness of advertising. Middle age, middle-income customers living within 10 miles (16.1 km) of the farm comprised the largest percentage of customers surveyed at the PYO operations, while middle age, high-income individuals who also live within 10 miles of the fruit stand were the largest group of respondents at the fruit stands. PYO customers spent an average of $10.30, and prepick consumers spent an average of $9.40 per visit. Less than 23% of all the respondents said that advertising influenced their shopping decision while >77% indicated that any type of advertisement did not influence their decision. Overall, convenient location was easily the major reason that customers decided to patronize a specific direct market outlet while personal referrals were second.
Partial budget analysis was used to evaluate soil treatment alternatives to methyl bromide (MeBr) based on their cost-effectiveness in the production of strawberries (Fragaria ×ananassa). The analysis was conducted for two geographical areas: the piedmont and coastal plain area (including North Carolina and Georgia) and the mountain area of western North Carolina, based on 7 years of field test data. The fumigation alternatives evaluated were Telone-C35 (1,3-dichloropropene 61.1% + chloropicrin 34.7%), Telone II (1,3-dichloropropene 94%), chloropicrin (Chlor-o-pic 99% and TriClor EC), InLine (1,3-dichloropropene 60.8% + chloropicrin 33.3%), and metam sodium (Vapam or Sectagon 42, 42% sodium methyldithiocarbamate). The MeBr formulation was 67% MeBr and 33% chloropicrin (Terr-O-Gas) with the exception of the earlier trials where a 98:2 ratio was used. In the piedmont and coastal plain area, the soil treated with chloropicrin showed the best results with an additional return of $1670/acre relative to MeBr, followed by Telone-C35 with an additional return of $277/acre. The projected return associated with shank-applied metam sodium was approximately equal to the estimated return a grower would receive when applying MeBr. Fumigating with drip-applied metam sodium, InLine, and Telone II as well as the nonfumigated soil treatment resulted in projected losses of $2182, $2233, $4179, and $6450 per acre, respectively, relative to MeBr. In the mountain area, all of the alternatives resulted in a projected increase in net returns relative to MeBr. The largest projected increase was $1320/acre for the InLine treatment, while the added returns for the TriClor and Telone-C35 applications were estimated to be $509 and $339 per acre, respectively. The drip-applied metam sodium application resulted in an additional return of $40/acre, and the added revenue for the nonfumigated soil treatment was $24/acre more than MeBr treatment. Although technical issues currently associated with some of the alternatives may persist, results indicate that there are economically feasible fumigation alternatives to MeBr in the production of strawberries in the southeastern U.S.