Horticultural Sciences Department

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Issue No. 584

The Vegetarian Newsletter 

A Horticultural Sciences Department Extension Publication on 
Vegetable and Fruit Crops 

Eat your Veggies and Fruits!!!!!

Publish Date: 
July 2013

Whole Farm Approach to Trap Cropping Strategies for Stink Bugs

Robert Hochmuth

Multi-County Extension Agent, University of Florida IFAS

 Suwannee Valley Agricultural Extension Center

When most people think of stink bugs, they usually think of a large green angular insect that stinks when it is crushed. But the world of stink bugs is much more diverse and complicated than that. Actually there are two species that are large and green, the southern green stink bug and the green stink bug. All adult stink bugs are shield-shaped, but the green and southern green stink bugs are both bright green and are among the larger members of the stink bugs commonly found in North Florida. Members of the stink bug “family” are very diverse in color with species that are green, brown, dark brown, metallic, or multi-colored. Most stink bugs are pests in that they are plant/crop feeders. However, to make it more complicated, some stink bug species are predators on other insect pests and therefore those species are beneficial. Since most are pests, this article will focus on those pest species.

Stink bugs (Pentatomidae) and leaf footed bugs (Coreidae) are important direct pests of many seed, fruit, vegetable, agronomic and nut crops. Stink bugs and leaf footed bugs are especially serious in the Suwannee Valley area of North Florida in vegetable crops tomato, pepper, and beans; and fruit crops peaches, nectarine, plum, blueberry and blackberry.  Perhaps the most common of all members of these two groups is the leaf footed bug (Leptoglossus spp.), a brownish colored bug with large flat leaf-shaped hind legs. This is, by far, the most prevalent of all stink bugs and leaf footed bugs found at the Suwannee Valley Agricultural Extension Center near Live Oak, FL. Stink bugs and leaf footed bugs have similar life cycles. The nymphs and adults feed on a variety of herbaceous weeds, grasses (bahiagrass) and many crops including corn, peach, plum pecan, peanut, soybean, green beans, pepper, eggplant and tomato. Four or five generations may occur in a single year. Stink bugs have piercing-sucking mouthparts. The mouth consists of a long beak-like structure called the rostrum. Salivary fluid is pumped down the salivary duct and liquefied food is pumped up the food canal. All plant parts are likely to be fed upon, but growing shoots and developing fruit and seed pods are preferred. The damage on fruit from the punctures is hard brownish or black spots. These punctures affect the fruit's edible qualities and decidedly lower its market value. Young fruit or grain growth is misshapen and it often withers or drops from the plant. Stink bug feeding can also alter the taste of the fruit.

 Stink bugs usually overwinter as adults but may remain active all year when the weather remains mild. Stink bugs are very mobile with the adults moving from crop to crop as the season progresses. When crop and weed hosts mature and die in the fall, stink bugs move into areas like woodlots looking for food and overwintering sites. Some stink bug species overwinter under the bark of trees. It is not uncommon for stink bugs to be found inside homes in the late fall as they try to find an overwintering location.

Stink bugs are difficult to control with insecticides. Recently they have become more common pests of many crops because of the reduction in broad spectrum pesticides that used to be commonly used in many fields and gardens. Most new, targeted, and “softer” insecticides are not effective against stink bugs. There are very few effective insecticides available to homeowners and organic growers. Because stink bugs and leaf footed bugs have many hosts and are very mobile, they can become a problem at any time during the season. They can be removed by hand or with a butterfly net from small plantings in gardens, but this is not practical in commercial fields. A trap called the yellow pyramid trap (Figure 1.); invented by University of Florida professor, Dr. Russ Mizell, exploits the visual behavior of the bugs and can be constructed and used to suppress populations. There is also a pheromone attractant available, methyl (E, Z)-2,4-decadienoate, that will enhance the capture rate of stink bugs. Used in conjunction with the yellow pyramid stink bug trap, stink bugs can be suppressed in small plots in north Florida and south Georgia. For further information on these traps read this document by Dr. Russ Mizell, http://nfrec.ifas.ufl.edu/MizellRF/stink_bugs/stink_bugs.htm

Another cultural practice gaining popularity as a method to manage stink bugs is trap cropping. Stink bugs and leaf footed bugs will feed on many crops and weeds, but they prefer to feed on specific parts of plants in specific maturity stages, primarily seeds in the milk stage, and certain other succulent areas that are present on individual plants for only a limited time during the season. Use of trap crops is based on the assumption that stink bugs can be attracted away from the main cash crop into smaller areas where they can be more efficiently managed. Trap crops must continuously provide food plants in the preferred stage that are more attractive than the cash crop. Small plantings of species such as triticale, sunflower (Fig. 1), sorghum, millet, buckwheat, soybean, field peas and okra, provide superior food plants for the bugs while also attracting their natural enemies. Once the stink bugs are attracted to the trap crop, we can better control them by spraying only the trap crop or hand collecting the stink bugs. Trials being conducted by UF/IFAS at Live Oak and Quincy are helping to identify varieties of trap crops that work the best. For instance, the sunflower variety, ‘Giganteus’ (Fig. 2), has been an excellent sunflower variety to use as a trap crop for leaf footed bugs, while others such as ‘Titan’ and ‘Mammoth’ have also been very effective as a trap crop. The rows of sunflower used as a trap crop are planted in a position between the overwintering sites and the edge of the vegetable field (Fig. 3). Another trap crop system showing excellent results at the Center in Live Oak for trapping stink bugs around large acreage grain crop fields was a five foot wide planting of triticale around the entire field perimeter. Triticale (a type of small grain) was seeded in the winter of 2012-2013 with a grain drill and grown to the bloom and early dough stage in April of 2013 when the stink bugs were migrating from the woodlands into the young grain fields. Once the leaf footed bugs build to sufficient populations, the “trapped” leaf footed bugs can then be sprayed and killed with inexpensive short-lived insecticides. The combination of triticale early in the spring followed by sequential sunflower plantings during the year, the leaf footed stink bug has been effectively managed in a 250 acre field area at the Suwannee Valley Agricultural Extension Center for two years. Only the trap crops were sprayed during the 2012 and 2013 seasons for control of the stink bugs. As a result of the strategically implemented trap crop program, no economic damage was found at the farm on susceptible crops including, but not limited to: tomato, pepper, eggplant, blueberry, and blackberry.

 More research is needed to further refine these systems, but in the meantime, demonstrations are being implemented on cooperating farms in the Suwannee Valley area. For more information on using trap crops, see this publication by Dr. Russ Mizell, http://nfrec.ifas.ufl.edu/MizellRF/stink_bugs/bug_trap_crops.htm

So, don’t be surprised stink bugs are still around and actually becoming more of a problem, but rather admire the unique adaptations this group of insects can make to survive. The yellow pyramid traps on a very small area basis and trap cropping systems on a much larger whole farm basis can assist farmers and gardeners by providing an advantage on managing stink bugs and leaf footed bugs.

Figure 1. Leaf footed stink bug on sunflower stem

Figure 2. Leaf footed stink bug on Giganteus sunflower

Figure 3. Sunflower trap crow row


Surfactant Increases Yield of Tomato Grown on Sandy Soil in Florida

Guodong Liu and Benjamin Hogue

Most soils in Florida are sandy. Sandy soil is high in large pores subject to free drainage and has low field capacity. Dry, sandy soil is water repellent, difficult to wet, and often forces water and solutes to flow via preferential paths (Ritsema et al., 1993). Thus, leaching is usually problematic in sandy soil. These properties of sandy soil challenge nutrient and water management for commercial crop production in Florida.

A surfactant is a compound that lowers the surface tension of a liquid (e.g. water), the interfacial tension between two liquids (e.g. water and pesticide) or that between a solid and liquid (e.g. soil particles and water). A properly selected surfactant may improve the wettability and quality of sandy soil. Surfactants have great potential to minimize nutrient leaching from sandy soil and enhance crop yield and nutrient use efficiency.  The objective of this trial was to evaluate the effects of a surfactant on: (1) nitrogen use efficiency; (2) phosphorus use efficiency; (3) potassium use efficiency; and (4) yield of tomato grown in sandy soil.

Materials and methods

This study was conducted with tomato (variety: Phoenix) at the Plant Science Research and Education Unit, UF/IFAS, Citra, Florida from August 13 to November 25, 2012. Drip irrigation was used with plastic mulch. Fertilizer application rates (lb/acre) were: 160, N as urea, 83, P2O5 as triple superphosphate, and 250, K2O as muriate of potash (potassium chloride, KCl).  Surfactant application rate (lb/acre) was 30 as Stockosorb® 660. This Stockosorb® 660 is a polymeric surfactant with a chemical essence of polyacrylate which can retain water as much as 216 g/g (Ghebru et al., 2007).* All chemicals should be used in accordance with directions on the manufacturer's label. The fertilizers and surfactant were completely mixed, banded on the central two inches of the false beds, and then disked and incorporated into the soil before bedding and planting. Plot size was 180 (30 × 6) square feet with 15 plants. A randomized complete block design was used with three replicates. Nutrient use efficiency (NUE, lb/lb) was defined as below:

where TYf and YT0: tomato yield (lb/acre) with and without fertilization; F: fertilization rate (lb/acre).

Results and discussion

The tomato plants in this trial reached the maximum size in 8 weeks after planting. The plants with Stockosorb® 660 were 15% (significant at p < 0.10) greater in both height and stem diameter than those without Stockosorb® 660 (Figures 1 and 2). These increments were similar to the results of Norway spruce (Sarvaš, 2003). The total number of tomatoes and tomato yield of the treatment were significantly greater than those of the control at p < 0.05. Particularly, the treatment had more than 2-fold large tomatoes than the control (Figure 3). Similarly, the N, P, and K use efficiencies of the treatment were all significantly greater at p < 0.05 than those of the control (Figure 4). The effects of Stockosorb® 660 on tomato yield and nutrient use efficiency may be attributed to the enhancement of water and nutrient retentions in the sandy soil amended with Stockosorb® 660, particularly, in the root zones of the tomato plants. Chemically, Stockosorb® 660 is a potassium polyacrylate. This polymer, on a mass basis, retained 216-fold water and 102.5% and 154.9% more ammonium and nitrate, respectively, than that retained by a selected soil without treatment with the surfactant (Ghebru et al., 2007). These characteristics apparently contributed to yield enhancement of tomato planted in the sandy soil measured in this field trial.

Figure 1. Plant size difference with or without Stockosorb® 660.

Figure 2. Plant size was 15% greater in plant height and stem diameter for the treatment with 30 lb Stockosorb® 660 per acre than those for the control without Stockosorb® 660. The difference was significantly different at p < 0.10. The vertical bars were the values of LSD2, 0.10 for the plant height and stem diameter.

Figure 3. The differences in the total yield and number of tomatoes for the treatment were both significantly greater at p < 0.05 than for the control. The vertical bars were the values of LSD2, 0.05 for the yield and total number of tomatoes.

Figure 4. The differences in nutrient use efficiencies were significantly greater at p < 0.05 in the treatment than in the control. The vertical bars were the values of LSD2, 0.05 for the N, P, and K use efficiencies.

Conclusions

Sandy soil quality improvement is necessary for growers to maximize nutrient use efficiency and yield for commercial tomato production and minimize nutrient leaching in Florida. The data from this preliminary study showed that the selected soil surfactant has the potential to improve water and nutrient use in sandy soil. This potential may provides us with a new strategy to manage water and nutrients more effectively in sandy soil. Not all surfactants may cause this same response in your soil and with your management strategies, but this strategy shows promise.

*Note that the use of trade names in this publication is solely for the purpose of providing specific information. The authors do not guarantee or warranty the product named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition.

Acknowledgements

We thank Dr. Ed Hanlon at the University of Florida for his suggestions and comments on the manuscript. Evonik Stockhausen LLC provided some Stockosorb® 660 for this trial.

References

Ghebru, M.G., E.S. duToit and J.M. Steyn. 2007. Water and nutrient retention by Aquasoil® and Stockosorb® polymers.  South African Journal of Plant and Soil 24(1): 32-36.

Ritsema, C. J., L. W. Dekker, J. M. H. Hendrickx, W. Hamminga. 1993. Preferential flow mechanism in a water repellent sandy soil. Water Resources Research 29(7):2183-2193.

Sarvaš, M. 2003. Effect of desiccation on the root system of Norway spruce (Picea abies [L.] Karst.) seedlings and a possibility of using hydrogel STOCKOSORB® for its protection. Journal of Forest Science 49(11): 531-536.


SEEPAGE VERSUS CENTRAL-PIVOT IRRIGATION FOR POTATO PRODUCTION IN MANATEE COUNTY

Teresa Salame, Guodong Liu, Bielinski Santos, and Loncoln Zotarelli, Crystal Snodgrass

Seepage is the most used irrigation system in Florida for potato production with the disadvantage of low water use efficiency; there are other systems available that claim to have a higher efficiency such central-pivot. With the aim of improving water use efficiency a potato grower in Manatee County had implemented central-pivot in three farms and studies are being conducted to compare both systems side by side, considering water use, yield and quality of potatoes. In a visit to the farms after a freeze event last winter, the grower showed us the differences he has seen between the two irrigation systems, the higher foliage coverage, greener plants (see figure 1) and less freeze damage (see figure 2) in potatoes irrigated with central-pivot as compared with seepage. Freeze protection wasn’t considered for him as a benefit of using central-pivot when he installed the system. We went back to the field after two different freeze events and collect data on freeze damage on potato plants under both systems (see figure 3), and found in the seepage irrigated plants more damage than central-pivot irrigated plants, for February 23 and March 8. These results suggest that central-pivot system could provide some freeze protection to potato. Further research need to be done to confirm these preliminary results.

Figure 1. Foliage coverage in seepage (left) versus central-pivot (right) irrigated potatoes. Parrish, Florida.

Figure 2. Foliar freeze damage in potatoes. seepage (left) versus central-pivot (right) irrigated potatoes Parrish, Florida on Februry 17, 2013.

Figure 3. Percentage of foliar freeze damage in potato plants taken after freeze or near freeze temperatures event for seepage and central-pivot irrigated potatoes in Parrish, FL season 2012-2013.

Acknowledgements

This study is supported by Southwest Florida Water Management District (13C00000017).

Mr. Alan Jones, Jones Potato Farm kindly provided the land for the research.