5.1 Pest Recognition and Biology

Why pests sit on every commercial sitting

Georgia's commercial applicator exam is not a county scouting contest, but you cannot pass Rule 40-21-3 by memorizing brand names. General Standard 4. Pests requires practical knowledge of three factors:

1. Common features of pest organisms and characteristics of damage needed for pest recognition
2. Recognition of relevant pests
3. Pest development and biology as it may be relevant to problem identification and control

Those three clauses are the whole core pests domain. Category exams — Plant Agriculture (21), Ornamental and Turf (24), Right-of-Way (27), Commercial Mosquito Control (41), Public Health (31), and the rest — add site-specific pests on top of this core. Private-applicator competency in the same rule uses a shorter version of the same idea: recognize common pests to be controlled and the damage caused by them.

University of Georgia Pesticide Safety Education Program (PSEP) General Standards manuals track the EPA/NASDA National Pesticide Applicator Certification Core Manual, 2nd edition, Chapter 1 (Pest Management). Chapter 1's first operational rule is identical to Georgia's: identify the organism and understand its biology before you choose a tactic. Spraying first and naming the pest later is the most reliable way to miss a General Standards item, a category item, and a real field.

The Core Manual defines a pest as an undesirable organism that injures people, desirable plants or animals, manufactured products, or natural substances. A pecan aphid depositing honeydew in a Dougherty County orchard can be a pest. A lady beetle eating those aphids is not. A tarnished plant bug blasting cotton squares is a pest; a similar-looking damsel bug is a predator. Recognition means you can separate those using common features (mouthparts, wings, body shape, growth habit) and characteristic damage (chewed squares, stippling, sooty mold, crescent egg scars, rhizome mats), not using the first jug on the truck.

Pest groups you must be able to tell apart

Chapter 1 groups pests so you do not treat every damaged leaf as an insect problem:

• Insects and related animals (mites, ticks, spiders, millipedes, sowbugs)
• Weeds (grasses, sedges, broadleaves)
• Plant pathogens (fungi, bacteria, viruses) and nematodes
• Mollusks (slugs and snails)
• Vertebrates (birds, rodents, and other mammals that injure the site)

Tomato spotted wilt virus (TSWV) in Georgia peanuts is a virus moved by thrips. A leaf-spot fungicide does not cure a virus. Pecan scab is a fungus; an insecticide does not replace a fungicide program. Dollar spot in turf is a fungal disease; a white-grub insecticide will not fill in the bleached spots. Palmer amaranth in cotton and peanuts is a pigweed, not "some grass," and yellow nutsedge is a sedge, not a grass — herbicide family has to match the weed, not the row crop's nickname.

Characteristic damage is a recognition tool

You will not have a laboratory at a Crisp County cotton gin dump, a Fort Valley peach block, or a Gwinnett lawn. You use symptoms (the host's response: wilt, chlorosis, stunt, dieback, blasted squares) and signs (the pest or its product: frass, mycelium, egg masses, cast skins, fungal fruiting bodies, mosquito larvae in a ditch).

• Chewing insects remove tissue. Cotton bollworm larvae chew squares and bolls. White grubs chew turf roots. Pecan weevil larvae feed inside the kernel. Plum curculio larvae feed inside peach fruit after the female cuts a crescent egg scar.
• Piercing-sucking insects leave stippling, hopperburn, honeydew, catfacing, or bites. Cotton tarnished plant bugs damage squares without bollworm-style chewed holes. Chinch bugs suck in thatch. Aphids on pecans produce honeydew and sooty mold. Mosquito adults take blood; that is not crop chewing.
• Mites are not insects. They stipple cotton, pecan, and ornamental leaves and may web. A mite flare after a broad-spectrum insecticide is often a secondary pest story, not proof that "the first product was too weak."
• Weeds compete for light, water, and nutrients and can host insects or pathogens. Identify grasses, sedges, and broadleaves, then annual versus perennial growth.
• Pathogens: fungi often show lesions, mycelium, or fruiting bodies (peanut leaf spot, pecan scab, peach brown rot, turf dollar spot). Bacteria may ooze or make angular spots. Viruses make mosaic, ringspot, or stunt without a fungus you can burn off the leaf. Nematodes are microscopic roundworms; a foliar insecticide is not nematode management.
• Mosquito recognition is stage-specific. Larvae ("wigglers") in standing water are not the same target as host-seeking adults. Container Aedes, floodwater species, and Culex in organically rich water use different sites. Category 41 still starts with species and stage, not with fogging because a resident was bitten.

Pest development and biology that change the tactic

Insects. Complete metamorphosis has four stages: egg, larva, pupa, adult. Larvae often do the plant feeding (bollworm, peachtree borer, white grub, mosquito larva, pecan weevil larva inside the nut). Adults may feed on different tissue, or may not feed on the crop at all. A foliar spray aimed at "bugs on the grass" does nothing to white grubs feeding on roots. An adulticide fog does not replace larval mosquito control in a backyard bucket. Incomplete (gradual) metamorphosis has egg, nymph, and adult. Nymphs look like small wingless adults and usually feed the same way (plant bugs, aphids, chinch bugs). If a scouting guide says to target nymphs or crawlers, that timing is biology, not a brand preference.

Weeds. Summer annuals germinate in spring, seed, and die in one warm season (crabgrass, Palmer amaranth). Winter annuals germinate in fall, overwinter, and seed in spring (henbit and chickweed in turf, orchards, and pecan middles). Biennials spend year one as a rosette and flower in year two. Perennials live more than two years and often spread by rhizomes, stolons, tubers, or bulbs. Johnsongrass on a Georgia Department of Transportation or utility right-of-way is a rhizomatous perennial. Kudzu is a perennial vine. A contact burndown that burns tops and leaves rhizomes or crowns is not "control" in the Core Manual sense. Nutsedge tubers explain why a grass herbicide disappoints on a peanut field shoulder.

Pathogens. Fungi and bacteria explode when leaf wetness and temperature match the disease. Peach brown rot and pecan scab are weather-and-tissue stories. Viruses need a vector — thrips for TSWV in peanuts is the Georgia example to keep. You cannot insecticide-away a virus already in the plant; you manage vectors, planting date, and host resistance (next section) to reduce new infections.

Key, occasional, and secondary pests

Chapter 1 also classifies pests by how often they justify management:

• Key pests cause major damage on a regular basis unless they are managed. Pecan scab in a humid Southwest Georgia orchard, Palmer amaranth in many South Georgia cotton and peanut fields, and plum curculio in peaches are key-pest patterns.
• Occasional pests become troublesome only once in a while because of weather, a disrupted rotation, or a particular flight (some armyworm years in turf or forage).
• Secondary pests become problems when a key pest is controlled — often because a broad-spectrum insecticide removed natural enemies. Cotton spider mites after a hard pyrethroid pass is the field story instructors use on purpose.

That classification is why identification is not optional color. Until you know the organism, you cannot know whether you are looking at a key pest, an occasional visitor, a disease, a nutrient deficiency, drought, or a secondary outbreak you are about to make worse. Section 5.3 turns that fact into IPM steps and thresholds. Here, lock the habit required by Rule 40-21-3: common features + characteristic damage + relevant pest + life stage before any product is mixed.