It’s August and field bindweed (Figures 1 and Figure 2), one of our most-persistent perennial weeds, is flowering. Although not statewide noxious, it’s locally noxious in Bennett, Bon Homme, Clarke, Lake, Stanley, and Yankton counties. Therefore, it’s the landowner’s legal responsibility to control the weed in these counties. Often called Creeping Jenny, hand-pulling will not control this weed due to its extensive root system. Mowing is not dependable either, as field bindweed can produce seed lower than the mowing height.
Identification and Management
Field bindweed can sometimes be mistaken for hedge bindweed and wild buckwheat (Figure 2). However, the basal lobes of field bindweed leaves are more pointed, whereas those of hedge bindweed are more angular or “squared off.” Both bindweed species are perennials, but wild buckwheat is an annual with leaves that are heart shaped. Wild buckwheat is typically found in annual production systems such as crop fields and vegetable gardens. Bindweed species are found in both annual and perennial systems (i.e. lawns or grasslands).
To kill most perennial weeds, one must kill the root with an herbicide application. Early fall applications are often best, as the weed sends more of its resources to the root at this time to prepare for winter survival. Translocated herbicides, such those belonging to the synthetic auxin family (group 4), also move to the roots with these resources. Examples of synthetic auxins include 2,4-D, dicamba, mecoprop, MCPA, and quinclorac. Herbicide blends containing quinclorac and others (2,4-D, dicamba, sulfentrazone, etc.) are often applied to lawns for crabgrass control in August. Quinclorac can also provide good field bindweed control, but it’s typically recommended for applications just prior to first frost (late-Sept./early Oct.). Little information is available on performance during August. When making an application to control crabgrass and field bindweed at the same time, evaluate the effectiveness and make a second application during early fall if necessary. Read the label to determine the appropriate interval between applications, which is usually 14 to 30 days depending on the product.
Rangeland, Pastures, Conservation Reserved Program, and Fallow
Picloram + 2,4-D (Grazon® P+D, Gunslinger® P+D, GrazonPD3TM) and quinclorac (Facet® L) are both effective. Picloram products are restricted use pesticides and therefore require proper licensing to purchase and apply. Apply when plants are actively growing, ideally when runners are 8-12” long. Lactating dairy animals can’t be grazed for 7 days after application. Hay can’t be harvested for 30 days after application. Animals must be removed from treated forage at least 3 days before slaughter. Do not apply within the area occupied by roots of treated trees.
The Facet® L label, however, recommends waiting until fall to make an application, especially if it can be made just prior to the first killing frost. A potential drawback when waiting until that time is that the plant will likely have produced viable seed. Hay can’t be harvested within 7 days after treatment, but other than that, there’s no haying or grazing restrictions.
Whatever herbicide program is utilized, continue to monitor for regrowth and plan for multiple years of treatment to get this troublesome weed under control. If crops are to follow picloram or quinclorac applications, pay close attention to post harvest intervals (PHIs). Small grains and sorghum can often be planted the following season. Most other crops either require 10 months or a successful bioassay.
