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Publication #ENY-881

Flower Thrips in Blackberries in Florida1

Oscar E. Liburd, Elena M. Rhodes, Elke Weibelzahl, and Sara E. Brennan2

Blackberries in Florida

Blackberry production is a small but growing industry in the state of Florida (Figure 1). In 2012, 306 acres of blackberries and dewberries were being grown in Florida (USDA 2009). Their numerous health benefits make them a good choice for Florida growers who want to diversify from traditional crops such as strawberries. The relatively short shelf life of blackberries makes them a suitable crop for “U-pick” and fresh-market operations in densely populated areas. In Florida, blackberries are typically harvested in May and June but little data is available on yield (Andersen and Crocker 2001).

Figure 1. 

A blackberry field in Florida.


Credit:

O. E. Liburd, UF


[Click thumbnail to enlarge.]

Blackberries grow best in deep, well-drained soils with a pH between 5.5 and 6.5. The ideal planting time is December through February, and proper irrigation and weed control are important during the first year. Blackberries are perennial deciduous bushes that require a certain number of chill hours to begin flowering (Figure 2). This limits production to more northern areas of the state of Florida. Breeders at the University of Arkansas continue to develop many cultivars that can be grown in north Florida (Andersen and Crocker 2001). Examples include ‘Apache’, ‘Arapaho’, ‘Chickasaw’, ‘Choctaw’, ‘Kiowa’, ‘Natchez’, ‘Navaho’, ‘Ouachita’, and ‘Shawnee’. Some cultivars have thorns, while others are thorn-less; the presumption is that thorn-less varieties are easier to manage (weeding, pruning, and harvesting). Similarly, other cultivars have been bred to grow upright, while others require a trellis system (Figure 1). For detailed information on blackberry production in Florida see Andersen and Crocker (2001).

Several potential pest insects and mites have been found on blackberries in Florida (Mizell 1993). The two most likely to become key pests are stink bugs and flower thrips (O. E. Liburd personal communication). Stink bugs feed on blackberry fruits (Mizell 1993) and have the potential to directly reduce yields if numbers are high enough.

Figure 2. 

Blackberry a) flowers and b) fruit.


Credit:

S. A. Brennan, UF


[Click thumbnail to enlarge.]

Varietal Effects

In north-central Florida, blackberry varieties flower at different times of the year and the duration of flowering depends on the variety. For example, ‘Kiowa’, ‘Choctaw’, and ‘Chickasaw’ begin flowering one to two weeks before ‘Natchez’ and two to three weeks before ‘Ouachita’ and ‘Arapaho’. Thrips populations tend to build up to higher numbers in varieties that flower earlier.

Flower Thrips

In general, flower thrips are very small insects (~1 mm in length) with yellowish to orange coloration (Figure 3). They can be distinguished from other insect orders by their fringed wings and rasping-sucking mouthparts. The most abundant thrips species found in blackberries in north-central Florida is the Florida flower thrips, Frankliniella bispinosa (Morgan) (Figure 3). In fact, 99.8 percent of the thrips sampled from plantings were identified as F. bispinosa. Flower thrips damage the flowers by feeding on the ovaries, styles, petals, and developing fruit, which can negatively affect berry production. The thrips species Microcephalothrips abdominalis (Crawford) and Thrips hawaiiensis (Morgan) also have been collected from blackberry flowers in Florida. Microcephalothrips abdominalis is known to reproduce in flowers of host plants but is not considered a major pest of small fruits. Alternatively, T. hawaiiensis is considered a pest of other fruit crops, including bananas and citrus. The predatory thrips Haplothrips graminis Hood (Thysanoptera: Phlaeothripidae) also have been collected in low numbers in Florida and tend to feed on arthropod eggs and other small insects.

Figure 3. 

A female Frankliniella bispinosa.


Credit:

Lyle Buss, UF


[Click thumbnail to enlarge.]

Monitoring

White sticky traps can be used to monitor flower thrips populations in blackberries (Figure 4). Although blue sticky traps are just as attractive to F. bispinosa as are white traps, it is difficult to see the thrips against the blue background (Finn 2003). Blue traps, therefore, are not recommended. Rodriguez-Saõna et al. (2010) found that sticky trap data were useful for predicting thrips flight activity and monitoring for the timing of insecticide applications. Traps should be placed as soon as the earliest varieties begin to flower and checked at least once per week because thrips populations can build up very rapidly.

Figure 4. 

White sticky trap on blackberry bush.


Credit:

S. A. Brennan, UF


[Click thumbnail to enlarge.]

Management

Minute pirate bugs (Orius spp.) may help to reduce thrips numbers in blackberries (Figure 5). Both adults and nymphs can be found in blackberry flowers. These insects are commercially available, but more research needs to be conducted to determine if releasing Orius spp. into blackberries will improve thrips control.

Figure 5. 

Orius spp. adult.


Credit:

E. M. Rhodes, UF


[Click thumbnail to enlarge.]

Several insecticides are registered for use on blackberries against thrips. These include reduced-risk insecticides that should have a minimal impact on populations of Orius spp. and other natural enemies. Insecticides should be applied early in the morning or in the evening to minimize impacts on pollinating insects. Remember to read labels carefully, as it is a federal violation to use a pesticide in a manner not specified on the label.

References

Andersen, P. C. and T. E. Crocker. 2001. The Blackberry. HS807. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/hs5104

Finn, E. 2003. “Developing Integrated Pest Management (IPM) Techniques for Managing Key Pests of Blueberries in the Southeastern United States." Masters thesis. University of Florida. Gainesville, FL.

Lewis, T., ed. 1997. Thrips as Crop Pests. New York: CAB International.

Liburd, O. E. and H. A. Arevalo. 2005. Integrated Strategies for Controlling Flower Thrips in Southern Highbush Blueberries. IPM-140. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/in637

Mizell, R. F., III. 1993. “Insect Management in Blackberries.” ENY-410 (IG069), Department of Entomology and Nematology, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL.

Rodriguez-Saona, C. R., S. Polavarapu, J. D. Barry, D. Polk, R. Jörnsten, P. V. Oudemans, and O. E. Liburd. 2010. “Color Preference, Seasonality, Spatial Distribution and Species Composition of Thrips (Thysanoptera: Thripidae) in Northern Highbush Blueberries.” Crop Prot. 29:1331–1340.

USDA. 2014. 2012 Census of Agriculture. United States Summary and State Data 1:526.

Footnotes

1.

This document is ENY-881, one of a series of the Department of Entomology and Nematology, UF/IFAS Extension. Original publication date October 2014. Reviewed October 2017. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Oscar E. Liburd, professor of fruit and vegetable entomology; Elena M. Rhodes, post-doctoral research associate in fruit and vegetable IPM; Elke Weibelzahl, former biological scientist in the fruit and vegetable IPM laboratory; and Sara E. Brennan, former graduate student in the fruit and vegetable IPM laboratory; Department of Entomology and Nematology, UF/IFAS Extension, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.