SWD-related losses in these industries vary by year and crop depending on management practices, weather conditions, time of the year, and geographic location. A primary motivation for focusing on the California raspberry industry is that California accounts for the majority of raspberry production in the U.S. and the raspberry industry accounts for the majority of economic losses due to SWD among berry crops. A second motivation is the magnitude of change in pest management practices; few of the SWD control practices used by raspberry producers were needed to prevent injury from other pests prior to its establishment. Economic losses in the California raspberry industry include the cost of managing SWD and the value of the fruit lost due to SWD infestations despite management efforts. First, we compute the cost of the chemical management programs and the labor-intensive sanitation practices implemented to mitigate SWD-related yield losses. Second, we calculate the industry level yield losses due to infestation. These components form an estimate of the full economic cost of SWD’s invasion into California raspberry production.Raspberry production is a valuable component of California’s agricultural industry. In 2013, raspberries were estimated to be the twenty-seventh largest crop in California by value of production. California accounted for 74% of all raspberry production in the United States. The United States is the third largest producer of raspberries in the world, producing 91,300 tonnes, after the Russian Federation and Poland,plastic seedling pots which produce 143,000 and 121,040 tonnes, respectively. Across all counties, California’s raspberry production was worth an estimated $239 million according to the United States Department of Agriculture’s National Agricultural Statistics Service , and $437 million according to California County Agricultural Commissioners’ Reports.
The difference in these estimates reflects that the NASS data report cash receipts to producers while the Agricultural Commissioners’ Reports estimate the total value of production. Figures 1, 2, 3, and 4 plot California raspberry hectares, production, yield per hectare, price per kilogram, and the total cash receipts between 2004 and 2013.Note that raspberry hectares multiplied by yield per hectare is equivalent to production, and production multiplied by price per kilogram is equivalent to total cash receipts. Four counties account for virtually all commercial raspberry production in California: Ventura, Santa Cruz, Santa Barbara, and Monterey.In 2014, Ventura County produced approximately 52% of California’s raspberry crop by value, $241 million, on 1,873 hectares. Raspberries are the third most valuable crop in Ventura County.Santa Cruz County produced approximately 28% of California’s raspberry crop by value, $131 million, on 979 hectares. Raspberries are the second most valuable crop in Santa Cruz County.Santa Barbara County produced approximately 10% of California’s raspberry crop by value, $45.2 million, on 591 hectares. Raspberries are the ninth most valuable crop in Santa Barbara County.Monterey County produced approximately 10% of California’s raspberry crop by value, $45 million, on 316 hectares. Raspberries are the sixteenth most valuable crop in Monterey County.Table 1 summarizes California raspberry production by county.Counties are listed from north to south along the Pacific Coast. Figure 5 identifies these berry-producing regions with a stylized map of California.Most commercial raspberry plantings in California have had an 18-month lifespan. The crop is planted in the winter and then harvested twice, first in the fall following planting and then in the subsequent summer. Both harvest seasons last approximately three months, with crews harvesting fruit every three days on average. Variations in harvest frequency depend on yields and pest management activities. Yields are low at the beginning and end of a harvest season, and peak near the middle of a season.
Pesticide applications may require an interval of time, depending on the particular pesticide, before normal harvesting activities can resume. This period is known as the pre-harvest interval , and it is determined by the U.S. Environmental Protection Agency. Occasionally, low yields are realized during the harvest season due to crop damage resulting from weather, pest activity, or other external factors. The summer harvest is typically larger than the fall harvest.Organically produced raspberries represent a significant share of total California raspberry production. In 2008 and 2011, California’s organic raspberry production was valued at $11.4 million and $8.98 million, respectively, according to the USDA-NASS. In 2012, 408 hectares of California raspberries were organically managed according to the University of California Agricultural Issues Center. Raspberry prices vary throughout the year, but on average organic raspberries are sold at a price premium. In 2015, the national average retail price of organic raspberries over the entire year was $3.52 per six ounce tray according to the USDA Agricultural Marketing Service. The average retail price of conventional raspberries over the same period was $2.55 per tray. The average California terminal market prices for organic and conventional raspberries were $3.29 and $1.97 per tray, respectively. California raspberries are a major export crop. In 2013, the combined category of raspberry, blackberry, mulberry, and loganberry exports was the twentieth largest export crop category by value in California. Raspberries account for the majority of the production volume and the total value of this category. This California export category was valued at $157 million, and accounted for approximately 85% of total US fresh and processed raspberry, blackberry, mulberry, and loganberry exports. 84% of these exports are received by Canada, 6% by Japan, and 5% by the European Union.
The presence of SWD has clearly increased production costs and caused yield losses for California raspberry producers through a variety of channels. Three previous studies have attempted to quantify the economic cost of the SWD invasion.However, these studies occurred within one or two years of the first SWD infestations in North America when information on the pest was still sparse and management techniques were rapidly evolving. We can improve on these original estimates now that much more is known about SWD biology, risks, and management. We briefly review these original studies before establishing new estimates of the economic cost of SWD in the California raspberry industry. Walsh et al. 1 and Bolda et al. 6 are the first studies to estimate the economic cost of SWD. These studies utilize yield loss estimates and observations for strawberries, blueberries, raspberries, blackberries, and cherries in California, Oregon, and Washington in conjunction with production data to calculate revenue loss estimates for each state and crop pairing. Walsh et al. assume a yield loss of 20% for all the listed crops in these states. As a result, the study estimates a total of $511 million in potential damages annually due to SWD. Bolda et al. continue the analysis by assuming the maximum reported yield losses of 40% for blueberries, 50% for blackberries and raspberries, 33% for cherries, and 20% for processing strawberries. The study concludes that potential revenue losses across these states and crops could be as large as $421.5 million given current prices.Goodhue et al. refine these estimates of lost revenue for the California raspberry and strawberry industries by including potential price responses into their estimates. This additional assumption reflects that as the production of raspberries and strawberries decreases,container size for raspberries the prices of these products may increase in response. The interaction between production and price is quantified with the inverse own-price elasticity of demand for each crop. The elasticity predicts the percentage change in price of a good in response to a 1% increase in quantity demanded. Drawing upon elasticity estimates established in prior studies, the authors conclude that SWD-induced yield losses could decrease California raspberry and processed strawberry revenues by up to 37% and 20%, respectively. The authors also evaluate the cost of different SWD-targeting insecticide applications and the cost of a specific conventional raspberry pest control program in California’s Central Coast region. The insecticide material and application costs are estimated to be $825.33 per hectare. However, these chemical applications may also provide incidental control of other pests. This implies that the estimate represents an upper bound of the potential chemical control costs associated with SWD.The revenue loss and management cost estimates in these prior studies can be substantially improved using current information about SWD-induced yield losses and management practices. Fruit losses due to SWD and SWD management costs have decreased over time as researchers and producers have developed and implemented better techniques for reducing crop losses.
We can also more accurately estimate historic yield losses now that more is known about SWD biology, its spread, and the efficacy of different management techniques. Lastly, we can now incorporate increases in labor costs into these SWD management cost estimates. Prior estimates of SWD-induced revenue losses were based on the maximum observed yield losses in different industries where SWD infestations occurred. These estimates provide information about SWD’s damage potential, but do not yield an accurate estimate of actual SWD crop damage. Actual crop damage is useful for estimating revenue losses due to SWD and will differ by year and production style. This analysis incorporates field trial results and expert opinions to estimate SWD-induced revenue losses for the California raspberry industry. SWD infestations directly reduce raspberry yields in two ways. First, fruit infested by SWD decay more quickly. These yield losses are difficult to attribute to SWD because the initial infestation is difficult to detect, and the accelerated decay has a similar appearance to decay caused by fungal diseases, bacteria, and yeasts. Second, raspberry shippers that detect SWD infestations may reject the entire delivery from the grower. Fresh fruit are held to rigorous quality standards. The risk of rejection of an entire delivery incentivizes growers to eliminate all visible deffects in harvested fruit. SWD infestations are more prevalent late in the year as the population grows until winter weather reduces the population.Further, raspberry production is fairly concentrated geographically and the leftover, overripe fruit from nearby fields’ summer harvest acts as a breeding ground for SWD. SWD infestations are also more prevalent in fruit destined for the processing market, where the price is lower than in the fresh market. Fruit intended for processing are harvested later in the season, tend to be riper because they are harvested less frequently, and receive less frequent pesticide treatments. SWD damage rates could change significantly in the future due to pesticide resistance development and the introduction of new SWD management practices, including introducing biological control agents. Recent studies in the US and Europe found that indigenous parasitoids had limited effect on SWD populations.However, in Asia, where SWD originates, several endemic parasitoids attack and develop from SWD. The original reports of SWD damage in the raspberry industry indicated that as much as 50% of production could be lost if SWD was left unmanaged.Yield losses of this magnitude occurred as raspberry producers first learned how to manage SWD, but are now uncommon due to implementation of extensive academic research and industry experience. According to private communications with conventional raspberry producers, they have managed to reduce SWD induced yield losses to less than 3% of production. In recently published reports, conventional raspberry producers that employ effective chemical management programs face virtually no yield losses due to SWD.This substantial reduction in yield losses is primarily attributable to two factors. First, conventional raspberry producers have access to cheap and effective chemical management options.Second, these producers are harvesting their crop more frequently in order to reduce the amount of time raspberries are susceptible to infestation. These observations of actual SWD-induced yield losses are consistent with field trial observations as well. Entomologists Kelly Hamby and Frank Zalom monitored traps and evaluated fruit samples for damage between October 2010 and December 2012 in both organically- and conventionally-managed raspberry sites. Analyzing the 40-fruit samples collected from these fields resulted in estimated yield loss observations for raspberry producers employing standard management practices at the time. SWD-induced yield losses for conventional producers in the study were estimated to be approximately 10% of production in 2011 and less than 1% in 2012. These estimated yield losses are consistent with those observed by De Ros et al. in Italy between 2011 and 2013. De Ros et al. estimated raspberry losses of 11.5% prior to i and 3.24% after the implementation of an integrated strategy. The yield losses observed in the UC Davis study were concentrated in the fall harvest.The summer harvest is hypothesized to experience less SWD pressure because the population grows throughout the year until cold weather arrives and lack of host fruit in the winter significantly reduces population levels.