Insect Pest Management: Scout and Use Thresholds to Maximize Profitability (Roberts) June 25, 2025
Cotton growth stages range from being planted and emerging to squaring and setting bolls. Weather conditions and the length of our growing season allow cotton to be planted from April to June. Regardless of planting date, it is vitally important to scout fields, use thresholds, and be timely with insecticide applications if and when needed. Much research has been conducted to develop thresholds, and field verification trials and experience have demonstrated they are the most efficient way to maximize profitability when managing insect pests. The goal of an Integrated Pest Management (IPM) program is not to eliminate all insect pests, but to manage populations so that economic returns are maximized.
In parts of Georgia there is significant acreage that most producers consider to be late planted. Should IPM programs be different on late planted cotton compared with early planted cotton? The simple answer is no, they are one in the same – scout and use thresholds. But there are a couple of considerations for thought. Cotton has an amazing ability to compensate from insect damage or other stressors which may impact fruit retention. Compensation takes time, and late planted cotton will not have as much time to compensate. In other words, if we make a mistake with insect management on late planted cotton the plant may not be able to fully compensate and may be more costly than a mistake on early planted cotton where the plant would have time to compensate.
Current insect pests in cotton now include cotton aphids, plant bugs, and stink bugs. Below are a few thoughts on how planting date affects each of these pests. Cotton aphids will ultimately infest 100 percent of cotton plants in the state of Georgia. During my career we have evaluated the impact of aphid control on cotton yields many many times. In summary we rarely see a yield response when spraying aphids. Most growers do not spray aphids and wait on the naturally occurring fungus which will crash populations. This fungus generally starts in southwest Georgia during late June or early July and moves north and east in time. The presence of gray fuzzy aphid cadavers is indicative of the fungus and once you see this sign across the field aphid populations will generally crash in less than a week. With that said there are times cotton would probably benefit from removing the stress placed on the plant by high aphid populations. Yellowing terminals or reduced growth would suggest to me that we need to treat aphids. On late planted cotton (i.e. June planted), high aphid populations could stress seedlings and delay maturity a few days so I tend to be more aggressive with aphid management on late planted cotton.
Tarnished plant bugs are being reported from some parts of Georgia and treatments are being made based on scouting and the use of thresholds. Aphids are present in most fields now and it just makes sense to use a plant bug insecticide which also has activity on aphids. During June and early July, we tend to observe higher plant bug populations on early planted cotton. Adult plant bugs are migrating from weedy hosts and squaring cotton is an attractive host plant that once a plant bug finds they will likely remain. On the flip side, later planted cotton may avoid this initial migration to cotton but will remain susceptible to plant bugs later in the year. During 2024 we observed issues with plant bugs in late August and September when we are in peak bloom for later planted cotton.
Stink bugs are a boll feeding pest and do not pose a threat to cotton until it begins setting bolls. Data clearly shows that later planted cotton is at greater risk to stink bugs compared with early planted cotton. Most insect pest populations build throughout the summer and ultimately will concentrate on green lush cotton later in the year. In closing, trust your scouting and use thresholds. Make good decisions on what pests are in the field and be timely when and if insecticides are needed.