The sugarcane borer, Diatraea saccharalis, is one of the most important above-ground pests of sugarcane in Florida. Although this insect's principal host is sugarcane, many other grasses have been reported as alternative hosts.
Significant damage results from the sugarcane borer tunneling within the stalk. This can cause a loss of stalk weight (tonnage/acre) and sucrose yield. The borer's tunneling into the stalk allows points of entry for secondary invaders including fungal, bacterial, and viral disease organisms. One investigation showed bored internodes produce 45% less sugar than undamaged ones. If the tunneling is extensive, death of the terminal growing point of the plant ("dead-heart") may result. Weakened stalks are more subject to breaking and lodging.
The foundation of an IPM program for sugarcane borer control is regular scouting. Scouting is necessary to estimate the infestation level and beneficial borer parasites. A regular scouting program will also increase the chances of detecting other pests that may be damaging the crop.
Fields should be scouted every 2 or 3 weeks from March through November. One Florida sugarcane company scouts each 40-acre field in at least 4 locations. At each location, 5 stalks are randomly sampled from each of 5 stools spaced 10 feet apart (5 stalks/5 stools/location). It is desirable to detect borers before they tunnel into stalks so that, if necessary, control measures can be applied before any damage to stalks occurs. Characteristic signs that plants are infested are pinholes in leaves, tiny holes into midribs, holes into stalks, and frass (light-brown fibrous waste material) at these holes. An infestation of borers can not be positively identified until the sugarcane borers are actually observed. Examine leaves, the whorl, and behind leaf-sheaths. Split stalks to detect borers tunneling inside stalks. Detecting 2 to 3 live larvae per 100 sampled stalks is generally thought to be enough to cause concern about economic damage. Whenever the economic injury threshold is approached, sugarcane borer larvae from a field should be dissected to determine the level of parasitism. If 50% or greater of the borers are parasitized, no chemical control is recommended.