The Vegetarian Newsletter
A Horticultural Sciences Department Extension Publication on
Vegetable and Fruit Crops
Eat your Veggies and Fruits!!!!!
Blueberry Consumption
By Lisa House and Allen Wysocki
Food and Resource Economics Department
The consumption of blueberries in the U.S. has been on the increase for the last two decades, from 42.3 to 345.4 million pounds between 1991 and 2010 (Figure 1). Per capita consumption of blueberries has increased from 0.17 to 1.11 pounds over the same period. Though there are some fluctuations in blueberry consumption, the general trend has been increasing, particularly in the last ten years when total consumption more nearly quadrupled from 73.1 to 345.4 million pounds (USDA). At the same time the industry saw increases in fresh blueberry consumption, consumption of frozen blueberries fluctuated, with increases from 1980 – 1990, but a more steady consumption from 1990 – 2010. Total consumption of frozen blueberries increased from 0.18 pounds per capita in 1980 to 0.33 pound per capita in 1990, where it held relatively steady until recently. Between 2007 and 2010, large increases were seen in per capita consumption of both fresh and frozen blueberries, with fresh consumption increasing 90% and frozen consumption increasing 56%.
Figure 1. Per capita consumption of fresh and frozen blueberries in the United States, 1980 - 2010
With the increases in demand for blueberries, prices have remained strong. The grower price for fresh blueberries increased from $0.88/pound in 1993 to $2.11/pound in 2007. Prices for processed blueberries also increased, from $0.33/pound to $1.52/pound over the same time period (USDA). Because Florida’s early-season southern highbush blueberries are the first cultivars to ripen in North America, the grower price in Florida is higher than that in other major blueberry production states. Fresh blueberries shipped from Florida received an average price of over $4 per pound before May 20 (Williamson et.al 2004).
To learn more about factors that influence blueberry consumption, the Florida Agricultural Market Research Center at the University of Florida conducted an online survey with adult participants in the Eastern half of the United States. Prior to preparation of the survey, focus groups were conducted in Jacksonville, Florida and Washington, D.C. to gain insight into consumption patterns and to facilitate construction of the survey instrument. The online survey was conducted (sample provided by Survey Sampling, Inc.) from September, 2010 through August, 2011, with a minimum of 350 responses collected each month. In total, 5,110 participants responded to the survey. The randomly recruited participants met the criteria of being an adult, primary grocery shopper (performs 50% or more of the household grocery shopping), who lived in Eastern half of the United States. Participants were first asked whether or not they had ever purchased fresh or frozen blueberries, followed by whether they had purchased fresh or frozen blueberries in last month. Purchase information was collected monthly to aid in consumer recall, as well as to better understand the impact of seasonality on purchases of both types of blueberries. Participants also answered questions about tastes and preferences regarding blueberries, as well as demographic questions. The following is a descriptive summary of results from this survey.
Overall, 84% of the respondents indicated they had purchased fresh or frozen blueberries at some time. There were statistically significant regional differences: 86% of participants in the Northeast reported consumption compared to 81% the Southeast. There were also differences in whether fresh or frozen blueberries had been purchased in the previous month depending on the time of year, as well as whether the respondent lived in the Northeast or Southeast region of the United States (the percent of respondents purchasing fresh blueberries increases during summer months, while frozen consumption tends to fluctuate from 30-40% of consumers, regardless of season) (Figure 2). The percent of respondents who reported not purchasing any blueberries in the previous month also differed depending on the time of year and region (Figures 2 and 3). This is not surprising that respondents would indicate reduced purchases during traditional off-seasons for blueberries.
Figure 2. Percent of respondents in Northeast and Southeast United States reporting fresh and frozen blueberry consumption in past month
Figure 3. Percent of respondents in Northeast and Southeast United States reporting no blueberry consumption in past month
Differences in overall preferences regarding fresh and frozen blueberries indicate that consumers generally like fresh blueberries more than frozen, as is expected with the recent trend to increase fresh consumption at faster rates (Figure 4). Participants also report eating blueberries for a variety of reasons. When asked how much they agree or disagree with a variety of reasons for eating blueberries, the largest percent of respondents indicated they eat blueberries because of the taste, followed by health. Price was not seen as a reason for eating blueberries by many approximately 70% of consumers. The only reason that significantly differed by region was taste, where consumers from the Northeast indicated taste was a slightly bigger reason than those from the Southeast, perhaps explaining the different levels of consumption in those regions.
Figure 4. Likeability of fresh and frozen blueberries
When purchasing blueberries, consumers report that the most important factors that influence them the most are the freshness of blueberries and the lack of appearance of mold. Following the top two factors were firmness, color, price, and size. This corresponds to focus group results that indicated that being able to see the blueberries to make sure they would not be soft or moldy is an important feature of packaging. Participants felt container size, where the blueberries were grown, and availability of samples were the least important factors of the nine they could select from.
To learn more about how important location of production is, participants were asked if they consider the location of production when purchasing fresh blueberries. Less than half (42%) indicated this was a factor. Participants were then asked how likely they were to purchase blueberries produced in their state, the United States, and imported. Those who felt strongly that location mattered were more likely to select blueberries from their state first, followed by the United States, followed by imported. Those that indicated location is not that important were not as likely to differentiate between blueberries from their state and the United States, but preferred either of these to imported blueberries.
Summary
The results from this survey verify many pre-conceived notions about consumers. Respondents in the Northeast reported a higher consumption of blueberries than respondents in the Southeast and consumers generally like fresh blueberries more than frozen. However, there are also some important messages about blueberry consumption. The largest percent of respondents indicated they eat blueberries because of the taste, followed by health. Price was not seen as a reason for eating blueberries by many approximately 70% of consumers. When purchasing blueberries, consumers feel freshness of blueberries and the lack of appearance of mold are important, likely identifying these factors as influencing the taste. Participants felt container size, where the blueberries were grown, and availability of samples were the least important factors they could select from. Those who felt strongly that location mattered were more likely to select blueberries from their state first, followed by the United States, followed by imported.
References:
U.S. Department of Agriculture [USDA] (2010, March) “Annual Data on U.S. and State Harvested Acreage, Yield, Production, Prices, Crop Value, Trade, and Per Capita Use of Blueberries,” Economics, Statistics and Market Information System, Economic Research Service, Washington, D.C.
Williamson, J.G., P.M. Lyrene, T.D. Hewitt and K.C. Ruppert (2004). “Alternative Opportunities for Small Farms: Blueberry Production Review.” Alternative Opportunities for Small Farms Series. Florida Cooperative Extension Service Publication #RF-AC008, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL.
Integrated Organic Agriculture Training in Dominica
Danielle Treadwell, Associate Professor, Horticultural Sciences, UF-IFAS, Gainesville, FL
Stuart Weiss, Agronomy Program Leader, University of the Virgin Islands, St. Croix, VI
Dominica? Where is that exactly? I had to look at a map, and then immediately accepted the offer to design and conduct a training on organic agriculture with my UVI colleague and HS PhD candidate student Stuart Weiss. The trip was funded by the Florida Association for Volunteer Action in the Caribbean and the Americas (FAVACA), a private not-for-profit organization established by then Governor Bob Graham in 1982. FAVACA responds to partner requests for training and technical assistance to improve the environmental, social and economic conditions in the region. In our case, FAVACA was approached by the Dominican Organic Agriculture Movement (DOAM), a private non-profit organization with a mission of outreach and education on organic production. Our program was also co-sponsored by Dominca’s Ministry of Agriculture and Forestry. In particular, we were asked to focus on soil and nutrient management for the tropics, not an easy task considering the current condition of the land, the physical and financial limitations of obtaining off-farm inputs, and the general lack of agricultural infrastructure.
The Commonwealth of Dominica is a small island nation in the Lesser Antilles in the Caribbean Sea. Christopher Columbus came upon the island on Sunday, November 3, 1493, and gave it the Latin name for Sunday Dominica. The island is rich with history, experiencing French then British rule, and finally declaring independence in 1978. Known as the Nature Island, Dominica’s 70,000 residents live on 290 square miles of lush tropical rainforest with many rare plants, animals and birds. The island is mountainous and is 4,747 feet above sea level at its highest point. The soils are volcanic in origin, and are composed of three different soil types that vary in the type of clay (1:1 or 2:1), the parent material (volcanic rock or ash), and amount of organic matter (higher elevations having less). There are several large farms on the island (500 acres or so) but most of the vegetable and fruit production occurs on small, diversified farms. Following a reduction in banana trade preferences, the agricultural community diversified its production by including coffee, cut flowers, and other tropical fruits such as mango, papaya and coconut. A variety of vegetables are grown including cabbage (head and leafy cultivars), carrot, sweet and hot peppers, cassava, sweet potato, yucca and tomato. The organic standards developed by DOAM are recognized by IFOAM, the global organic organization that oversees policy and programs of organic agriculture for all countries involved in organic agriculture (think of IFOAM as the United Nations for organic agriculture). DOAM and the farmers of Dominica are working hard to build a robust food system that includes certified organic farmers who meet standards consistent with US and/or EU national organic standards so that they can trade with neighboring islands like Martinique and Guadeloupe. The island’s main port is in its capital, Roseau, and roads are primarily on the perimeter of the island with minimal access to the interior.
Our training took place in community centers or agricultural outreach offices across the island as well as on farms. At each location, the training was attended by farmers (15-40), school children (10-25 primary school and high school) and several representatives of DOAM and Dominica’s Ministry of Agriculture and Forestry. The agenda was similar among locations. We began with a morning session in the classroom, followed by a break for a delicious lunch, then an afternoon practical in the field where we applied some of the concepts that were discussed in the morning. The major topics covered were organic certification, soil and nutrient management, and terracing. In a few locations we were also able to cover pest management and marketing, depending on the direction and interest and needs of the attendees. The farmers were very engaged in the entire process. Obstacles to productivity included access to a diversity of seed, lack of awareness of erosion control methods, how to identify allowable inputs, and marketing. In the morning, we spent a considerable amount of time in discussion on these topics, including the definitions of genetically modified seed, hybrids and heirlooms and the phenotypic and genotypic consequences of saving seed from each; terracing strategies and how ancient cultures such as the Mayans were able to have highly productive agricultural systems because of their use of terracing, developing a business community among farmers including the importance of establishing an economy for farm services (such as cooperative buying and transplant production), and increasing market access, especially to the island’s tourism enterprises.
Afternoons were spent on two primary activities: 1) demonstrating the terracing method using a homemade t-stick and an A-frame fitted with a plumb bob (Figure 1), and 2) exploring ways to assess soil nutrient status using inexpensive tools and observation (Figure 2). We used pH strips to talk about cation exchange, and dug roots of legumes to explore nitrogen fixation. The school children in particular were eager assistants and enjoyed identifying Rhizobia nodules, collecting soil for sampling, and finding insects to identify and discuss. The farmers were eager to construct their own A-frames, and realized the importance of protecting their most valuable natural resource – the soil (Figures 3 and 4). There was an “aha-moment” when farmer attendees admitted the root balls of banana that were elevated because the root ball had been exposed over time due to soil erosion on their steep slopes.
Overall, it was a fantastic experience. We did not mind the bumpy ride in the rental, or the crab that hitchhiked in the car for 36 hours and seem to make his presence known at unexpected times. We view this experience as our first contribution to what we see as a long-term commitment. We have donated many materials to the DOAM library (Figure 5), including the A-frame and are preparing a packet of follow-up materials promised to the group. Despite the limitations in infrastructure and resource availability, the farmers clearly loved what they did and shared a vision of a robust and diverse food economy. We look forward to additional opportunities to strengthen the food system in Dominica any way we can.
Figure 1. Weiss demonstrates the use of an A-Frame to establish contours and terraces in hillside farming.
Figure 2. Farmers engaged in a discussion about soil pH and nutrient availability with Treadwell.
Figure 3. Result of slash and burn methods. The road is immediately below.
Figure 4. Standard practice for hillside yam planting.
Figure 5. Books that were donated to the DOAM library.
PEPPER WEEVIL, ANTHONOMUS EUGENII CANO (COLEOPTERA: CURCULIONIDAE), AN IMPORTANT PEST OF PEPPER
D. R. Seal, UF/IFAS Tropical Research & Education Center and M. L. Lamberts, UF/IFAS Miami-Dade County Extension
Pepper. Peppers, Capsicum annuum L., are the primary host of the pepper weevil, Anthonomus eugenii Cano. Various types of peppers and the pepper weevil have coexisted for several hundred years. Thus, knowledge of the origin of pepper is essential to an understanding of the origin of the pepper weevil and its subsequent geographical distribution. The word “pepper” itself is related to Columbus’ discovery of the New World in 1492 (Vinje and Chile 2004). On his way to West Indies Columbus sampled a plant he thought was related to black pepper, Piper nigrum L., which he dubbed “pepper.”
Peppers, sweet or hot (Fig. 1), belong to the family `Solanaceae’,genus `Capsicum’, species `annuum’. According to some etymologists, capsicum comes from the Greek ‘kapto’ meaning “to bite.” Another group of etymologists say the word derives from the Latin word `capsa’ meaning "box," due to the box-like shape of bell peppers.
Figure. 1. Various types of peppers
Neither of these etymologies explains the origin of hot and sweet pepper. Alphonse de Candolle, a botanist, produced convincing linguistic evidence for the South America origin of the genus Capsicum. By 1492, at least four different species of pepper were being cultivated by Native Americans. Later on, approximately 50 years after Columbus brought home peppers, they had been adopted in Africa, India, Asia, China, the Middle East, the Balkans, Central Europe and Italy.
Pepper weevil (PW), Anthonomus eugenii Cano. The pepper weevil is an insidious pest of all known varieties of peppers. The origin of PW is tied to the origin of pepper plants. It is thought to have originated in Mexico, from which it spread throughout South America. The first report in the US came from Texas in 1904 (Capinera 2002). After its first appearance in the US, it was found in California in 1923 and in Hawaii in 1933. Pepper weevil was reported in Florida in 1935; it reached Puerto Rico 1n 1982. Pepper weevil was detected for the first time in Canada in 1992. It has not yet been reported from Europe.
Figure 2. Pepper weevil adult 
Figure 3. Pepper weevil infested fruits
Pepper weevil adult (Fig. 2) is a small insect, 2.0 - 3.5 mm long and 1.5 - 1.8 mm wide. PW is blackish and has a long snout at the tip of its head which is used to puncture host tissue for feeding and egg laying purposes. The snout is slightly curved at the anterior end. Dorsally, the body looks like a half circle. The adult is adept at hiding in the pepper canopy. It is an active flier and is difficult to catch. It is an economically important pest of all varieties of pepper. Infestation of pepper weevil causes fruit drop (Fig. 3).
Eggs (Fig. 4) are oval-shaped and have a grayish color. They are 0.53 mm long and 0.39 mm wide. Females of PW oviposit inside flowers and fruits (Riley, 1990). Young buds are preferentially selected by the females over other parts of the pepper plant. Oviposition starts within 2-7 days of emergence. In general, the oviposition period lasts 75 days, during which time the average PW female lays 1.67 eggs/day (potentially 125 eggs/female). About 60% of the eggs produce adults. The post-oviposition period is generally 5 days, but can be as long as 108 days.
Figure 4. Pepper weevil egg on pepper fruit
Larvae, (Fig. 5) on hatching, bore inside the host where they develop by feeding host tissues (Fig. 5). The first instar is 1.0 mm (0.8 – 1.5 mm) long, and lives for 1.7 d. The second instar is 1.9 mm (1.3 – 2.6 mm) long and lives for 2.2 d. The third instar is 3.3 mm (2.2 – 5.0 mm) long and lives longer (8.4 d) than the first and second instars.
Figure. 5. Pepper weevil larva and its feeding damage inside the fruit
Pupae (Fig. 6) are 2.8 mm long and lives for 4.7 days. At the end of pupal development, the adult weevil emerges out of the larval-pupal cell through a small round hole.
Figure 6. Pepper weevil pupa
Percentage mortality of PW development stages (Table 1). Most of the mortality occurs at the egg stage which ranges from 23 to 31% depending on temperature. Percentages of mortality decrease with the advancement of development stages. Thus, pupae suffer lower rate of mortality than the egg stage.
Table 1. Percent mortality of development stages of pepper weevil at three constant temperatures.
Development stages | 20oC | 25oC | 30oC |
Egg | 72.4% | 69.2% | 73.2% |
Larva | 90.2% | 82.8% | 76.4% |
Pupa | 96.0% | 90.8% | 85.9% |
Seasonal abundance (Fig. 7). The pepper weevil population can maintain itself year-round when the host is available. PWs start appearing in pepper fields when plants are about 4 week old, though they are not resident at that time. Once a pepper plant starts producing buds and flowers, PWs move into the field and start visiting terminal leaves, buds and flowers. At this stage their presence can be discerned by carefully checking young leaves, buds, flowers and fruit for pinprick-like punctures. In southern Florida, the infestation of PW is low from September to December but increases from January to July. The peak population of PW has been recorded from April to June.
Figure 7. Seasonal abundance of pepper weevil in 1999 and 2000.
Diel pattern of distribution (Fig. 8). Diel activity of pepper weevil was determined using relative sampling method where Trece’s yellow sticky traps and Plato’s Bait stick traps were deployed in a `Jalapeno’ pepper field. In an established pepper field, pepper weevil remains active during the daylight hours. Activity increased as the number of hours of daylight increased. The highest activity was observed at 4 p.m. followed by 2 p.m. and 10 a.m. It is recommended that a management program should be applied during these peak activity hours.
Figuere 8. Diel pattern of abundance of pepper weevil adults in two different traps.
Alternate Hosts include other Solanaceous plants such as Petunia spp., Chrysalis, eggplant, datura, nicotiana, nightshades, horsenettle, buffalo bar, and Jerusalem cherry. However, information on the feeding and reproductive status of pepper weevil on these host plants is not clear.
Management. Infestation of pepper by pepper weevil turns the calyx yellow (Fig. 9) and increases fruit drop. Unfortunately, many growers only begin to recognize PW infestations when fruits start to drop. At this stage, it is difficult to control PW, even using 2 to 3 applications per week of conventional insecticides. In most instances, control failure is due to an insufficient knowledge of effective insecticides and of improper timing of applications during the season.
Figue 9. Pepper weevil infested fruit with yellow calyx attached to the plant
Detection of PW infestation. Detecting adults at the initiation of infestation in a field is the principal step in managing pepper weevil. Failure to detect the arrival of the first group of adults will result in the failure of a management program. Detection of adults can be achieved by adopting the following methods:
a. PWACT (Pepper Weevil Attract and Control Tube) (Fig 10a). A yellow sticky PVC tube, 80 cm. long and 3 cm. diam. (Plato Industries, Houston, Texas) can be used to detect pepper weevil adults. Tangletrap® glue (Tanglefoot Company, Grand Rapids, MI) was used to coat the outside of the stick. The efficiency of the yellow sticky stick can be increased by adding Trece pepper weevil pheromone TRE 8420 + 8462. Eight to ten tubes/acre is a good way to get information about a pepper weevil infestation. The tubes should be checked regularly and replaced every 2 weeks.
b. Yellow sticky cards (Fig. 10b). This is a commonly used method employed by researchers and pest control personnel. Traps should be stationed at the perimeter of the field at the rate of 8 – 10 traps/acre. Trap height should be adjusted such a way that the yellow sticky cards (15 x 15 cm) stand 1 foot above the plant canopy. Traps should be in place at least two weeks before flowering. Since the efficiency of sticky traps decreases with time, they should be replaced every week.
c.
10a 10b
Figure 10. Use of two different traps for detecting pepper weevil adults
c. Direct checking. Pepper weevil prefers to visit leaf buds (un-open bundle of leaves) and freshly open new leaves where they rest and probe for food and oviposition sites. The probing hole can easily be detected by visual observation. Take care not to disturb the target leaves. This method of detection of pepper weevil can be accomplished by observing either adults or their holes or both. Direct checking is time consuming and needs patience.
d. Sweep net. In theory, an insect sweep net can be used to detect PW adults on pepper plants. The problem is that this method causes flowers and fruits to dropping off and destroys branches.
Varieties with Resistance to Pepper Weevil. An important long-range goal is to develop the joint use of resistant varieties and augmentative releases of a biocontrol agent as the primary factors in a PW integrated pest management system. If this could be achieved, then chemical control could be held in reserve for use in circumstances in which the two biological tactics prove insufficient.
At the Tropical Research and Education Center in Homestead, we tested 11 varieties of commonly grown pepper in Florida (Table 2). Among these, the percentage of PW infested fruits was higher in `Indian Long Hot’ pepper than in any other varieties. `Hot Cherry’ and `Habanero’ had a lower percentage of PW infested fruits among the 11 varieties in all 3 studies (Fig. 11). Varietal differences in regard to the percent infested fruits per plant indicate that some varieties possess a stronger natural resistance to the PW infestation than other varieties. Attempts should be made to further enhance such resistance through plant breeding.
Table 2. Different types of pepper, their variety and source
Pepper type | Variety | Source |
Cubanelle | ‘Biscayne’ | Peto Seed Co. |
Hot Cherry | ‘Cherry Bomb’ | Peto Seed Co. |
Indian Long Hot | ‘Indian Long Hot’ | Peto Seed Co. |
Santa Fe | 'Santa Fe Grande’ | Peto Seed Co. |
Jingle Bell | 'Jingle Bell' | Peto Seed Co. |
Pimiento | `Pimiento’ | Unknown |
Super Chili | `Super Chili’ | Johnny’s Select Seed, Co. |
Thai Chili | ‘Thai Dragon’ | Johnny’s Select Seed, Co. |
Hungarian Wax | ‘Bounty' | Johnny’s Select Seed, Co. |
Jalapeno | ‘Grande’ | Peto Seed Co. |
Habanero | ‘Habanero’ | Peto Seed Co. |
Figure 11. Mean numbers of pepper weevil (pw) infested fruits in each variety on three harvesting dates (1st, 2nd, and 3rd) in Year (2010) or indication of how far apart the harvest dates were – weekly for example.
Biological control. Catolaccus hunteri Crawford (Hymenoptera: Pteromalidae) is a wasp (Fig. 12) that attacks immature stages of pepper weevil. It is external parasitoid of various weevils including pepper weevil. It is the most common parasitoid of pepper weevil in United States, Mexico and other pepper growing regions (Seal et al. 2002). C. hunter was successfully introduced to Hawaii from Guatemala to control pepper weevil. Hunsberger and Peña (1997) reported this pest from acerola or Barbados cherry, Malpighia glabra (L.) (= punicifolia L.) in Homestead, Fla. Schuster (2007) reported suppression of pepper weevil in an organic bell pepper farm by weekly releases of C. hunteri at the rate of 1600 adults per 0.2 ha plot. Release of parasitoid should be initiated several days before the first bloom. Rearing of the parasitoid is fairly easy since it can be mass reared on garbanzo beans at 25o- 30oC (Fig. 12).
Figure 12. Catolaccus hunteri adults and their rearing on four different beans in a laboratory condition
Cultural practices. Pepper weevil has several alternate hosts. Among these, nightshade is the common one where pepper weevil survives the pepper free period. Nightshade plants should be destroyed around pepper fields. A pepper-free period should be maintained to break the normal cycle of reproduction. Fallen infested pepper fruits should be collected and destroyed to keep from increasing the population. If possible, infested fruits with yellow calyxes should be harvested and destroyed.
Chemical control.
- Pepper weevil is an insidious insect with cryptic character that is difficult to detect at the beginning of the infestation. To avoid economic damage, it is important to start a management program one week before the emergence of flower buds. At this stage they can be detected using yellow sticky cards, or detected and killed by using Plato’s yellow sticky tubes (PWCAT) impregnated with oxamyl or malathion at the rate of 8-12 tubes/acre. Once they are detected, a spray program should be initiated immediately by using Kryocide® (10 lbs/acre) in combination with Neemix® 4.5 (6 ozs./acre) + Trilogy 70EC® (7% v/v). Subsequent applications of insecticides should be de made by choosing effective insecticides in a program. Studies conducted in 2008 at the Tropical Research and Education Center, Homestead, Fla. for managing pepper weevil showed that thiamethoxam (Actara®, Syngenta Crop Protection, IRAC Group 4A ) and oxamyl (Vydate®, DuPont Crop Protection, IRAC Group 1) were effective in reducing pepper weevil infested fruits (Fig. 13).
Figure 13. Mean numbers of pepper weevil infested fruits in `Jalapeno’ plants treated with Actara® and Vydate®.
In a second study conducted in 2009, insecticides used to managing pepper weevils included oxamyl (Vydate®), thiamethoxam (Actara® and Platinum®, Syngenta, Crop Protection, IRAC Group 4A), imidacloprid (Admire®, Bayer, IRAC Group 4A), thiacloprid (Calypso®, Bayer Crop Protection, IRAC Group 4A), cryolite (Kryocide®, Pennwalt Corporation). In this study, there were 7 foliar applications of insecticides in each program. Soil applications of insecticides were made both at planting and at flowering. All treatments showed significant reduction of pepper weevil infested fruits except Admire® (Table 3).
Table 3. Mean numbers of PW infested peppers/plot treated with various insecticides
programs, Fall 2011
Treatments | Rate/acre | Mean no. infested fruits |
Vydate (3 times) Actara (4 times) | 2pt 2oz | 55.31 bd |
Vydate (5 times) Actara (2 times) | 2pt 4oz | 36.56 cd |
Platinum (at planting) Platinum (at bloom) | 4oz 4 oz | 104.50 b |
Admire (at planting) Admire (at bloom) | 16oz 16oz | 186.19 a |
Cryolyte (1-2 Calypso 4SC (3-5) Vydate(6-7) | 10 lb 3oz 2pt | 51.81 bd |
Cryolyte (1-2) Actara(3-4) Vydate (5-7) | 10 lb 4oz 2pt | 28.13 d |
Vydate (1-7) | 2 pt | 66.75 bc |
Control | 241.56 a |
Method of application or subsequent times of foliar application of each insecticide is shown in
parentheses
In the third study, conducted in 2010, the insecticides used were cyazypyr (HGW86 10SE, DuPont Crop Protection, IRAC Group 28, a diamide insecticide); thiamethoxam (Actara®) and bifenthrin (Brigade®, FMC, IRAC group 3). Cyazypyr in rotation with bifenthrin, provided significant reduction of pepper weevil infested fruits (Table 4).
Table 4. Mean numbers of pepper weevil infested `Jalapeno’ pepper fruits/plot on two harvest dates when pepper plants were treated with various insecticides on four dates at weekly intervals, Spring 2010.
Treatment | Mean Pepper no. fruits/plot | ||
Rate lb a.i./acre | 29 April | 9 May | |
HGW86 10SE | 0.066 | 15.00bz | 33.50a |
HGW86 10SE | 0.088 | 16.25ab | 19.50bd |
HGW86 10SE | 0.134 | 15.00b | 26.25ab |
HGW86 10SE | 0.176 | 14.00b | 14.75cd |
HGW86 10SE + MSO | 0.88 + 0.50 | 17.00ab | 20.50bc |
HGW86 10SE + Brigade 2SC | 0.88 +6.4 oz | 15.00b | 10.00d |
Actara | 3.75 oz | 19.25ab | 11.50cd |
Control | 24.75a | 31.00ab | |
zMeans within a column followed by a same letter do not differ significantly (P > 0.05, DMRT).
In the fourth study, conducted in 2011, cyazypyr in a management programs with thiamethoxam (Actara®), oxamyl (Vydate®), acetamiprid (Assail®, UPI, IRAC Group 4A), and esfenvalerate (Asana®, DuPont Crop Protection, IRAC Group 3) provided significant reduction of pepper weevil infested fruits (Table 5). Management programs containing esfenvalerate showed greater reduction of pepper weevil infested fruits.
Table 5. Mean numbers of PW infested peppers/plot treated with various insecticides in programs, fall 2011.
Mean numbers of PW infested peppers/plot
Treatments | Rate (oz)/A | 16 Nov. | 23Nov. | 30 Nov. | 07 Dec. | 14 Dec. |
HGW86 10 SE | 20.5 | 0.25 | 1.75b | 5.25b | 15.00b | 32.00b |
Actara 25WG Vydate 2SL DPX HGW86 10 SE Actara 25WG | 4.0 32.0 13.5 4.0 | 0z | 1.50b | 4.25b | 9.50bc | 15.25c |
Actara Vydate DPX Asana Actara | 4.0 32.0 13.5 9.60 4.0 | 0 | 1.00b | 4.00b | 4.50c | 9.00c |
Actara Vydate DPX Assail Actara | 4.0 32.0 13.5 1.10 4.0 | 0 | 1.00b | 5.75b | 7.25c | 12.00c |
Actara Vydate Asana Actara | 4.0 32.0 9.60 4.0 | 0 | 1.25b | 3.00b | 5.75c | 9.50c |
Untreated check | 0.50 | 4.75a | 14.00a | 33.50a | 66.00a |
zMeans within a column followed by a same letter do not differ significantly (P > 0.05).
References
Capinera, J.L. 2002. Anthonomus eugenii Cano (Insecta: Coleoptera: Curculionidae). http://entomology.ifas.ufl.edu/creatures/veg/beetle/pepper_weevil.htm
Hunsberger, A.G. and J.E. Peña. 1997. Catolaccus hunter (Hymenoptera: Pteromalidae), A parasite to Anthonomus macromalus (Coleoptera: Curculionidae) in south Florida. Florida Entomologist, 80(2): 301-304.
Riley, D.J. 1990. Refined sampling methodology and action thresholds for the pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae). Ph. D. Dissertation, University of Florida, Gainesville.
Schuster, D.J. 2007. Suppression of Anthonomus eugenii (Coleoptera: Curculionidae) pepper fruit infestation with releases of Catolaccus hunter (Hymenoptera: Pteromalidae). Biocontrol Science and Technology, 17(4): 345-351.
Seal, D. R, P. A. Stansly, and D. J. Schuster. 2002. Influence of temperature and host on life history pa rameters of Catolaccus hunteri (Hymenoptera: Pter omalidae). Environ. Entomol. 31: 354-360.
Vinje, E. and C. Chile. 2004. The origin of chile peppers. http://www.cosmicchile.com/xdpy/kb/chile-pepper-history.html.
Urban Plantings of M. paniculata May Not Be a Major Inoculum Source of ‘Candidatus Liberibacter asiaticus’, the Causal Agent of Citrus Huanglongbing
Shouan Zhang
Tropical Research and Education Center, University of Florida, Homestead, FL 33031
Abigail J. Walter, David G. Hall, and Yong Ping Duan
U.S. Horticultural Research Laboratory, USDA-ARS, Fort Pierce, FL 34945
Huanglongbing (HLB) is the most destructive disease of cultivated Citrus spp. in Florida and worldwide. In Citrus spp., HLB incites leaf chlorosis, reduces growth, causes small, asymmetric, or lopsided fruit, and finally results in death of the trees. Although Koch’s postulates have not been completed, HLB is strongly associated with three species of bacteria i.e. ‘Candidatus Liberibacter asiaticus’, ‘Ca. L. americanus’, and ‘Ca. L. africanus’. The bacteria are vectored by one of two species of psyllids: Diaphorina citri Kuwayama or Trioza erytreae (Del Guercio) (Bové, 2006). In Florida, HLB is associated with ‘Ca. L. asiaticus’ (Tyler et al., 2009) and vectored by D. citri.
Both D. citri and ‘Ca. L. asiaticus’ infest a number of host plants besides cultivated Citrus spp. Although germplasm varies in susceptibility to psyllid infestations, at least 23 genera within the family Rutaceae were reported to be hosts of the psyllid. Bergera koenigii, Citrus macrophylla, “commercial citrus”, and Murraya paniculata have been reported to be preferred host plants of the psyllid (Westbrook et al. 2011). HLB epidemiology in a citrus grove may be affected by plants in the surrounding landscape that act as host of the vector and the disease.
M. paniculata is a popular ornamental plant in Florida. As an alternative host species, it has the potential to be especially problematic for Citrus production. M. paniculata is an excellent host for D. citri (Halbert and Manjunath, 2004) and can also harbor ‘Ca. L. asiaticus’ (Deng et al., 2007). However, ‘Ca. L. asiaticus’-infected M. paniculata often do not show HLB symptoms, and may be less affected by the bacterium than Citrus spp. There are concerns about the potential for this plant to serve as an asymptomatic reservoir of ‘Ca. L. asiaticus’ inoculum for nearby Citrus plantings. D. citri regularly disperses from and to citrus throughout the year (Hall and Hentz 2011). In Florida, D. citri adults collected from M. paniculata in garden centers, residential plantings and nurseries, and nymphs collected from nurseries, have been found to be infected by ‘Ca. L. asiaticus’ (Manjunath et al., 2008). Because M. paniculata may flush frequently, D. citri is able to reproduce on this plant at times when they could not reproduce on Citrus spp., which may increase area-wide populations of the psyllid and increased infestations in nearby Citrus plantings. Concern about the potential for spread of the vector and HLB led the State of Florida to restrict the conditions for propagation and sale of M. paniculata in the state (Clark 2007). No programs to manage existing plantings of M. paniculata have been implemented in Florida.
Although research has shown that HLB can be transmitted to and from M. paniculata by D. citri, questions remain about the real importance of M. paniculata plantings as inoculum reservoirs for ‘Ca. L. asiaticus’. While ‘Ca. L. asiaticus’ is sometimes detected in M. paniculata, only a small amount of polymerase chain reaction (PCR) product is amplified, indicating that fewer bacterial genomes are present (Deng et al., 2007, Morgan et. al., 2012). Under laboratory conditions, titers of ‘Ca. L. asiaticus’ in psyllid-inoculated M. paniculata drop to undetectable levels within several months post infection (Damsteegt et al., 2010). Furthermore, although ‘Ca. L. asiaticus’ can be transmitted to sweet orange from M. paniculata, none of five orange trees back-inoculated with the Florida strain of ‘Ca. L. asiaticus’ developed HLB symptoms in a quarantined greenhouse (Damsteegt et al., 2010). Finally, infection levels of HLB in the field have been consistently low both in M. paniculata and in psyllids developing on this plant in Florida (Walter et al. 2012). Similarly in Brazil, in a survey conducted after ‘Ca. L. asiaticus’ had become dominant over ‘Ca. L. americanus’, only 4% of 661 suspect samples from urban M. paniculata plantings in the State of São Paulo contained detectable levels of ‘Ca. L. asiaticus’ (Lopes et al., 2010).
In order to determine the importance of M. paniculata plantings as a reservoir inoculum source of HLB, a year-long survey was conducted in eight urban plantings of M. paniculata in east-central Florida (St. Lucie and Palm Beach Counties) to characterize ‘Ca. L. asiaticus’ infection rates in M. paniculata plants and associated psyllids. Infection revealed by sensitive quantitative PCR using primers targeting two prophage genes of ‘Ca. L. asiaticus’ (Morgan et. al., 2012) was very low. Less than 1% of psyllids and 1.8% of plants were detected to be positive for ‘Ca. L. asiaticus’ (Table 1). Further confirmation with qPCR primers targeting ‘Ca. L. asiaticus’ 16S rDNA revealed that all plants and psyllids were ‘Ca. L. asiaticus’- negative except for one psyllid. These results indicate that the titer of ‘Ca. L. asiaticus’ was very low in M. paniculata and associated psyllids, suggesting that urban plantings of M. paniculata are a minor source of ‘Ca. L. asiaticus’ inoculum. To what extent regulating the M. paniculata market in Florida reduces HLB in commercial citrus remains to be determined.
Table 1. Number of M. paniculata samples and psyllids reared with number of positive plant samples and psyllids (in parentheses) by the LJ900 primers targeting two prophage genes of ‘Ca. L. asiaticus’ for each site and date of a survey in St. Lucie and Palm Beach Counties, FL
Date | Site | Total | |||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | ||
M. paniculata Apr 2010 Jun 2010 Aug 2010 Oct 2010 Dec2010 Feb 2011 Total | 30 (1) - 12 (0) 30 (0) 30 (0) 30 (0) 132 (1) | 30 (2) - 10 (0) 30 (0) 30 (0) 30 (1) 130 (3) | 30 (1) - 11 (3) 30 (0) 30 (1) 30 (0) 131 (5) | 30 (0) - 12 (1) 30 (0) 30 (0) 30 (1) 132 (2) | 30 (1) - 17 (2) 30 (0) 30 (1) 30 (0) 137 (4) | 30 (0) - 15 (0) 30 (0) 30 (0) 30 (2) 135 (2) | 30 (1) - 13 (1) 30 (0) 30 (0) 30 (0) 133 (2) | - - 9 (0) 30 (0) 30 (0) 30 (0) 99 (0) | 210 (6) - 99 (7) 240 (0) 240 (2) 240 (4) 1029 (19) |
Psyllid Apr 2010 Jun 2010 Aug 2010 Oct 2010 Dec2010 Feb 2011 Total | - 4 (1) 15 (0) - 5 (0) 30 (0) 54 (1) | 19 (1) 20 (0) 1 (0) - 21 (0) 7 (0) 68 (1) | 31 (0) 16 (0) 13 (0) 30 (0) 1 (0) 3 (0) 94 (0) | 19 (0) 4 (0) 30 (0) 9 (0) 16 (1) 25 (0) 103 (1) | 2 (0) 30 (0) 23 (0) 14 (0) 14 (0) 30 (0) 113 (0) | 6 (0) 28 (0) 9 (1) 9 (0) - - 52 (1) | 17 (0) - 10 (0) 7 (0) 26 (0) 17 (0) 77 (0) | - 8 (1) 23 (0) 17 (0) 30 (0) 30 (0) 108 (1) | 94 (1) 110 (2) 124 (1) 86 (0) 113 (1) 142 (0) 669 (5) |
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