PEST MANAGEMENT
Critters that feed on the all-important root system of turf plants deserve a close look . Sure , leaves do the hard work of photosynthesis , creating sugars and carbohydrates , but half of the heavy lifting is acquiring moisture and nutrients from the soil . Without roots , that doesn ’ t happen . Keeping root-feeding pests at bay is critical and needs to be a foundational part of the maintenance protocol and budget .
SCOUTING FOR SUBSURFACE FEEDERS IS HARD When it comes to insects that feed underground , you can ’ t see what might be lurking ( and eating ) with all of the leaves and thatch in the way . It ’ s easy to spot stem rust spores on grass blades – the leaves turn orange and leave deposits on your shoes – but not so much with soil-active creatures . In fact , without a proactive approach to pest management , the “ out of sight , out of mind ” mindset can be pervasive .
Several sampling techniques are effective , starting with recordkeeping . Documentation of insect infestations that have been encountered is invaluable . Records don ’ t need to be sophisticated ; simple phrases in a yearly notebook can suffice . Basic maps of recent outbreaks add real value as well . As a management technique , recordkeeping helps to know what to look for from year to year .
The tools for scouting are inexpensive and likely to be on hand in the toolshed . A sod spade ( aka square-nosed shovel ), heavy-duty pocketknife and a golf cup cutter are easy to use and really helpful for extracting soil , thatch and possibly subsurface-feeding insects . Some of these pests can also be forced from their hiding places by using soap flushes and pouring them on suspect areas . The soap will irritate caterpillars and weevils and drive them to the surface for counting and identification .
Regardless of which tool is used , a “ down on your hands and knees ” posture should be utilized . In areas
Damage from white grub feeding . Photo by John C . Fech . previously injured or spots where damage symptoms are observed , remove the sod and start looking / scanning for anything that looks like it could be a responsible culprit . While inspecting , it ’ s likely that other insects and arthropods such as earthworms , centipedes , pill bugs and sowbugs are likely to be present .
Using your eyes in this manner is particularly important , not only for spotting potential responsible insects , but also for noting the condition of the soil , presence of water drainage limiting layers and the extent of the thatch buildup . All of these factors play a role in overall insect management .
KNOW WHAT YOU ’ RE UP AGAINST WHITE GRUBS As famous sports broadcaster Keith Jackson would say , grubs are “ the granddaddy of them all .” They are sort of the poster child for subsurface feeders . Several species of white grubs can damage sports turf including masked chafers , black turfgrass ataenius , Japanese beetles and May / June beetles . All of these grubs damage turf in their larval stage , except for Japanese beetles , which can cause injury in both the adult and the larval stage .
A good “ species separator ” for white grubs is to simply measure their size ; the smallest one is the black turfgrass ataenius , about half of the size of a small fingernail or 1 / 4 inch . The next largest is the Japanese beetle ’ s larval stage which is about twice that size . The largest ones , the masked chafers and May / June beetle , whose larvae start small , reach 3 / 4 inch in size . You can also familiarize yourself with the grub ’ s posterior abdominal tip and the spiny hairs that develop there . Different species of grubs have different “ raster patterns ” that are diagnostic .
Black turfgrass ataenius adults are black ( obviously ) in color and quite small at about 1 / 4 inch in size . They overwinter in loose soil , pine needles and leaf litter and begin moving into turf areas in mid-spring . Soon after , larvae hatch and begin feeding on turf roots . Feeding occurs for four to five weeks , then their life stage changes to a resting pupal form for a couple of weeks followed by emergence of adults . In mid-summer , if weather conditions are conducive , a second generation of beetles will develop and prepare to overwinter by mid- to late fall . Large numbers of ataenius larvae are required to cause turf injury .
Japanese beetles have the reputation of being voracious plant feeders and are known to feed on the roots , fruits , flowers and foliage of more than 300 landscape plants , as well as turfgrass . Adults are active from mid- to late summer when egg laying occurs . Their reputation is well deserved – a result of feeding on the roots and rhizomes of most turf species and cultivars . If present in sufficient numbers , severe damage can result from their feeding in a relatively short period of time . Adults are easily identified sportsfieldmanagementonline . com March 2023 | SportsField Management
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