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Invasion plan
Scouting and sampling for insect pests is the best way for superintendents to save their ornamentals.
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| Like other leaf munchers, Japanese beetles will devour whole sections of leaves and ruin the appearance of ornamentals. Photos by John Fech |
The chair of your green committee is hitting his approach shot to the No. 7 green.
As he considers whether the 6- or 7-iron is best for this distance, he notices some browned-out spruce trees that frame the green. He becomes so distracted that he shanks his ball into the front bunker. After recording double-bogey-7, he makes his way to the next tee, only to see the same symptoms on the privet hedge that lines the opposite side of the tee area. He starts mumbling about the intelligence and abilities of you, the superintendent.
Hopefully, a little bird is flying overhead, hears his rant and lets you in on his observations before the green chair does. And hopefully, you have the skills to identify the cause of each problem, determine why it’s happening and make appropriate management decisions. Successful control of ornamental pests begins with an effective insect monitoring program. This article discusses observational and management techniques that will help superintendents keep insect pests at bay.
Scouting and sampling are the hallmarks of a sound IPM program. It all starts with proper pest identification and knowing where the insects are — or where they will be in the future. Once these matters are taken care of, half of the pest control battle is won.
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| Maple bladdergalls are small, but some types of galls can reach several inches in diameter. |
Tools of the trade
The first step in sampling and scouting for insects is to identify the plant and get to know the normal growth pattern, leaf size and shape, stem color and flower. Federal Reserve inspectors spot counterfeit money by becoming so familiar with the actual currency that when they look at fake currency, it is easy for them to spot. Similarly, the eyes and experience of each golf course staff member are the most valuable tools in your sampling and scouting arsenal.
The second step is to ensure that every staff member has a full set of simple sampling tools, including a hand lens, screwdriver, pocket knife, sheet of white cardboard, collection container and a notebook for recording insect presence and damage. These low-tech tools can help you uncover and identify the insects that are damaging your plant and those that are merely hanging out. For example, suppose you suspect a blue spruce tree has a spider mite problem. Simply tap a suspected mite-infested branch over your white sheet of cardboard and examine the cardboard with your hand lens. If mites are present, you will see the tiny greenish-brown mites scurrying around on the white surface.
Now let’s review some of the insect groups you may want to include in your scouting and sampling program.
Leaf munchers
This category includes caterpillars (bagworms, armyworms, webworms, tent caterpillars, inchworms, loopers, walnut caterpillars, leafrollers), beetles (Japanese beetles, rose chafers, elm leaf beetles), sawflies, leaf cutter bees and grasshoppers.
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| Pests like this redhumped oakworm are relatively easy to identify. |
Symptoms of damage
Munchers of tree, shrub and flower leaves are relatively easy to identify, or at least their damage will be apparent. These critters eat whole sections of a leaf. When you look at damage from a leaf muncher, you will see chewed out areas, holes in the leaf, or the upper or lower leaf epidermis missing.
Sap suckers
This category includes aphids, scale insects, thrips, whiteflies, leafhoppers, treehoppers, plant bugs, lace bugs,
spittle bugs and mites (not actually an insect, but a pest
nonetheless).
Symptoms of damage
The name for this group is quite appropriate in that they pull liquid plant juices out of the leaves and stems as if they were at Jamba Juice sucking on a pineapple-banana smoothie. Instead of a straw, however, they use piercing-sucking mouthparts to extract their treat. Infested leaves may become curled and take on a speckled, pale, grayish or lackluster appearance. Stems tend to be shriveled and dryer than noninfested ones.
Galls and gall makers
This category includes gall wasps, psyllids, aphids, phylloxerans, gall midges and eriophyid mites.
Symptoms of damage
Galls appear like bumps on a log, except they are bumps on leaves or stems. Insect and eriophyid galls come in all shapes, sizes and colors from red to green to brown, and from oval to round to pyramidal. Some form structures that resemble a witch’s broom. While the majority of these galls are relatively small, in the 1⁄8- to ½-inch range, others can reach several inches in diameter.
Borers
Borers include round- and flat-headed borers (emerald ash borer, red-headed ash borer, locust borer, pine sawyer) and caterpillar borers (clear-winged ash borer, viburnum borer, peachtree borer).
Symptoms of damage
These insects often attack trees and shrubs under stress. The first noticeable symptoms are thinning and subsequent dieback of the foliage. Injury is caused by borer tunneling in the canes or trunk. Tunnels are packed with sawdust-like excrement, and holes may be visible in the bark. Infested plants may die if the damage is severe.
Once you know which group of insects your critter belongs to, the list of possible culprits begins to narrow and a Web search for further information is made much easier. With the name of the plant and type of insect, you’re well on your way. This information also will be critical when choosing your control strategy and, if necessary, selecting an appropriate insecticide.
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| Sap suckers such as these sumac aphids pull plant moisture from leaves and stems, causing leaves to curl and become speckled. |
When to look
Take it from us … or at least from the king of timing, Henny Youngman — timing is everything. Henny knew the importance of delivering punch lines with the right amount of waiting. Too soon or too late, and the joke wasn’t funny.
Build a “likely pests” calendar for each group of ornamentals on the course — the evergreen trees, the shrubs, the perennials, the deciduous trees. For example, your course has three kinds of evergreen trees — spruce, fir and pine. Research and develop a list of pests commonly associated with each tree species in your area, including spider mites, bagworms and needle miner for spruce, and tip moth, needle scale and sawflies for pines. Make an entry recording when damage usually first appears in your area and the treatment window when the pest is most readily controlled.
Purchase and install a “pest lookout” board for your shop. Update it weekly by posting information and photos from your files, university Extension publications, news releases and the Web to provide your crew with an instant pest activity update. For example, depending on your location, your pest lookout for the week of May 23 might include checking juniper shrubs for bagworms and annual plantings for aphids. Train every employee to be observant and routinely scout for insects, diseases, weeds, nutritional deficiencies, etc., as they go about their other duties.
Where to look
The easiest and surest way to locate insect and mite pests is to look where you find the damage. A careful and thorough inspection of the leaves, trunk and stems will usually provide good clues as to which insect is causing the damage. However, two factors stand in the way of accurate diagnosis and may therefore require additional scouting and sampling.
First, insect damage often mimics injury from fungal diseases. A good example occurs when leaf miners attack hawthorn trees. The insect larvae tunnel into the mesophyll or inner tissues of the leaf, devouring it from the inside. Yet from outward appearance, the damage is often thought to be a fungal leaf blight, such as Septoria or Cercosporella.
Second, for most ornamental plants, one half of the live tissue is in the soil and invisible to casual inspections. Sure, there are lots of aboveground feeders, but root damage can occur from many sources, including root rot, girdling roots and even hardpan soils. Unfortunately, it’s just not feasible to look at the underground parts of most woody ornamentals. However, with many annuals, groundcovers and herbaceous perennials, it’s relatively easy to dig up and examine the roots.
Third, the most obvious symptoms of insect damage may be associated with tissue that is mostly or completely dead. Looking for insects in these sites is usually not helpful, as the insects will likely have moved on to more succulent parts of the plant. Therefore, it is important to look at the obviously damaged areas, but also at the portions of the plant that are adjacent, or on the fringe of the original injury; that’s where the offending insects are most likely to be found.
Another location-sampling method involves observing the activity of other insects or animals. For example, it is not uncommon to find yellow jacket wasps associated with bark and leaf aphids that infest small ornamental trees such as crabapple, hawthorn and cherry. These wasps are not pests of the tree per se, but are actually feeding on the sugary exudate called honey dew that is being deposited by aphids or scale insects on the leaves of the tree. Likewise, lady beetles are often abundant on plants with heavy aphid infestations.
Finally, it is always wise to concentrate scouting and sampling efforts in areas of the golf course where leaf munchers, sap suckers, gall makers and borers have been a problem in the past. These areas with a history of damage are more likely to be reinfested year after year.
Record keeping
Record keeping is an important aspect of your IPM program, especially when adjusting your management practices from one year to the next. These notes take only a few minutes to write down, but will be invaluable in the future. When pests are encountered, jot down a few notes in your maintenance log regarding pest species, date of infestation, specific location of infestation, infestation level and control measures employed. Weather conditions and accumulated rainfall amounts are also valuable pieces of information. Record keeping helps identify potential hot spots of insect activity, which enables you to anticipate future infestations. Early detection and timely treatments are very powerful and effective tools in your pest management arsenal. Record keeping also helps your year-to-year planning and the preparation of maintenance budgets. If there are known areas of likely pest reinfestation, you can allocate adequate funds to deal with this issue.
In the final analysis, scouting and sampling are important steps in your overall pest management decision-making process. If no pests are found, perhaps there is another cause for the observed damage. Remember, many non-insect causes, including pathogenic diseases, mechanical injury and nutritional deficiencies, can be confused with insect damage.