Timing Is Everything: Plant Bug Scouting for Differently Aged Fields

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It has been a tough year for cotton across the state. As we move toward squaring and bloom stages, it is essential to plan plant bug scouting strategies depending on crop development. Over the past week, we have been scouting plant bug populations across the state (map).

Notes from the field: In a normal growing season, cotton development is much more consistent within and among fields. In 2020, we are seeing considerable development variation in cotton at the field and farm level. Over the past week, we have been surveying plant bug infestation across the state to better understand where these pests are at economically damaging levels.

One remarkable issue is the variation in square development. Unfortunately, irregular cotton development within fields and across farms really impacts standardized scouting and management recommendations. As a result, we need to be thinking about field-level management decisions for key early to mid-season pests.

Plantbug fieldmap

Squaring cotton fields surveyed for plant bugs and other secondary pests in 2020.

In the southern counties, we scouted fields with 3-4 reproductive nodes that were adjacent to fields that have no squares (Fig. 1). Moreover, poor stand establishment and/or variable development across individual fields was also common (Fig. 2). At the farm level, matching scouting approaches for plant bugs with the stage of the field will be very important to ensure the appropriate plant bug monitoring technique matches the maturity of the cotton field being scouted (see resources below).

More concerning, we picked up large plant bug counts in southern counties (Hoke, Scotland, Lenoir, Montgomery Counties). Plant bugs are not a consistent pest in these southern counties, however, the uptick in plant bug populations mean that diligent scouting will be essential to protect yield in these areas.

A few plant bug nymphs were detected in Nash and Wilson counties, suggesting that scouts should be looking for both life stages soon. As the cotton crop moves into the later stages of squaring and early bloom, we anticipate that there is the potential for lower square retention where localized plant bug hot spots pop up.

Field

Figure 1. Eight to ten node cotton was common in some counties.
Figure 2. Irregular stands creates a challenge for accurate scouting of square retention.

Other pests: We detected a few green and brown stink bugs in square stage cotton. Three-cornered alfalfa hoppers were at low levels in a few of the less mature fields in Nash County. Cotton aphids were detected at low levels in Martin County. Neither of these infestations were at an economic threshold, however, persistent scouting and timely threshold-based sprays will be essential for primary (plant bug, stink bugs, bollworm) and occasional secondary pests (aphids, mites) this season.

Addressing the plant bug problem: Understanding which tactic to use for squaring or bloom stage cotton is essential. Because fields are so variable this season, scouting activities between the pre-bloom and bloom-stage period of cotton will need to be specific to individual fields or areas within fields (in a replant situation). Although this tailoring scouting activities to individual fields will be a challenge, a bit of prevention could make a real difference during this challenging growing season. Specific pre- and post-bloom plant bug scouting information is available, as are recommendations for plant bug management.