THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL
|Pastures damaged by chinch bugs in South Florida
For questions or comments regarding this publication contact: Dr. Joao Vendramini, University of Florida, IFAS
South Florida experienced challenging rainfall conditions in 2017, with a prolonged drought in the spring and above average rainfall in June and July. These conditions changed forage, weed, and pest patterns and culminated in unusual forage damage by chinch bugs.
Chinch bugs are common pests in St. Augustine grass lawns, causing millions of dollars in damage for homeowners, with sparse reports of chinch bugs damaging pastures, primarily limpograss. However, we have received several reports of chinch bugs damaging limpograss, bermudagrass, stargrass, and bahiagrass in South Florida in 2017.
Chinch bugs thrive during the warm and wet summer months, and infestations usually reach maximum levels in early July. Female chinch bugs deposit eggs close to the soil, sometimes underneath the dead forage thatch on the base of the canopy, where a large number of adults and nymphs gather at the base of the plant. An infested pasture shows brown colored areas, usually round shaped, which typically starts in water stressed areas. Infestations are usually not evenly distributed in a pasture. Chinch bugs drain the sap of the forage, turning the forage from green to brown, which can subsequently die. To test for chinch bug presence, producers can use the floatation method, where an approximately 10 inch diameter and 1 feet tall pvc pipe is inserted in the soil and filled with water. The filling process should be continuous for few minutes, until the soil is saturated and the pvc is filled with water. If chinch bugs are present, they will float after few minutes. The test should be conducted in the transition area, between the brown and green forage.
Photo at left: Southern chinch bug, Blissus insularis Barber. From left to right: nymph, short-wing, and long-wing adults. Credit: Ronald Cherry, UF/IFAS
Pastures with excessive forage accumulation in poorly drained soil are particularly susceptible to chinch bugs. The thick thatch on the base of the plant provides a favorable habitat for chinch bugs to feed and reproduce. Therefore, the best cultural practice to control chinch bugs is to maintain the forage at the recommended stubble height (Table 1) and if possible, decrease the amount of thatch by burning the pasture in the spring. Proper soil pH and fertilization allow the plants to have a greater forage and root mass and be more resilient to chinch bug infestations. The fertilization program needs to be balanced with grazing and/or harvest to avoid excessive forage accumulation.
Stockpiling limpograss during the autumn for subsequent winter grazing is the most used forage conservation practice for beef cattle production in South Florida. Limpograss is usually cultivated in poorly drained soils and has significant herbage production during the summer months. High soil moisture can make it difficult to mechanically harvest the excessive amount of forage during the summer, which creates a conducive environment for chinch bug proliferation. Therefore, the recommendation is to graze limpograss pastures to the recommended stubble height during the summer and start the stockpiling period after September to decrease the chances of chinch bug infestation.
Although there are many different chemical control options for chinch bugs in lawns; there is no insecticide registered for chinch bug control on pastures. Chemical control in lawns has not been effective due to development of populations resistant to insecticides. On pastures, chinch bugs are usually underneath the thatch, which protects them from insecticide contact. If insecticides, such as Mustang, Sevin, Tracer, etc., are applied to control other insect pests, some suppression of the chinch bug population will occur. However, the effectiveness of the chemical control is highly variables.
- In pastures with history of chinch bug infestation, burn off the dense thatch of forage in the spring.
- Graze or harvest the grass in the summer to avoid excessive herbage accumulation
- Start the limpograss stockpiling period after August.
- Spraying for other insects may provide partial control of chinch bugs
Photo at right: Pasture damaged by cinch bugs in Martin County (07/20/2017). Photo by Joe Vendramini
Species Target stubble height (inches) Bahiagrass 2 Bermudagrass 5-7 Stargrass 6-8 Limpograss 8-10
Table 1. Target stubble height for different forage species in South Florida
If you have any questions about this article, please contact me at email@example.com or 863-735-1314.
On September 26, from 8:15 a.m. - 3:30 p.m., the UF/IFAS Range Cattle REC will host an in-service training providing an overview of the 2017 FCA Beef Enhancement Projects conducted in Ona. To view the agenda and register, go to http://fcep-ona.eventbrite.com or call 863-735-1314 ext. 204.