Matthew Bley and I were out at Cold Spring Orchard last week, fertilizing the blueberries and collecting some data on weed growth. The bindweed is out, and although it may look small now, it is about to become severe.
We also noticed a bittersweet vine poking up through the mulch – thank you to both Jake and Matthew for spotting it. These are two of the most difficult weeds to manage in a perennial orchard, so I am going to take the opportunity to highlight these two perennial vines.
Hedge bindweed
Scientific name: Calystegia sepium (L.) R. Br.
Identification: Twining herb, hairy or smooth stems, alternate leaves 1.5-6 inches long, heart- or arrow-shaped, with a pointed tip. Leaf lobes are squarish and angular near the petiole. Flowers are singular in the leaf axil, white or pink, trumpet-shaped, and 1.25-3 inches across1.
Reproduction: Mostly spread by thick horizontal roots, although seeds are also viable. Seeds are produced in egg-shaped capsules with 2 chambers containing 2 seeds each.
Similar species:
- Field bindweed (Convolvulus arvensis L.). Field bindweed leaves have more rounded lobes and tip (rather than angular lobes and tip in hedge bindweed). Field bindweed can have up to 5 flowers in the leaf axil and the flowers are smaller than hedge bindweed.
- Morningglory species (Ipomoea spp.). Morningglories are annuals, so even though the flowers and growth habit look very similar to bindweeds, they are important to distinguish. Different morningglory species have different leaf-shapes, but all of them are broader than bindweed leaves, which are more oblong. Morningglory leaves are also generally larger, more heart-shaped, and have rounded basal lobes.
- Wild buckwheat (Polygonum convolvulus L.). This is also an annual plant, and the leaf looks very similar to a bindweed leaf. If you look at the stem, wild buckwheat will have an ocrea that wraps around the node. This is a dead give-away that it is wild buckwheat rather than bindweed. The flowers are also very different. They are small, inconspicuous, and greenish-white.
Oriental Bittersweet
Scientific name: Celastrus orbiculatus Thunb.
Identification: Climbing deciduous woody vine, alternate leaves 3-4 inches long, rounded to obovate, with bluntly toothed margins. Inconspicuous green/white flowers in the spring. Leaves turn yellow in the fall before many native plants and female plants produce distinctive yellow capsules with red seeds that are visible in the winter2.
Reproduction: Mostly spread by sprouting from the roots, especially after cutting, and seeds. Vines with seeds are sometimes collected and used as decorative wreathes, which leads to further spread.
Similar species:
- American bittersweet (Celastrus scadens L.). American bittersweet is native to the United States. It has more ovate leaves (football-shaped) than Oriental bittersweet, which has more rounded leaves.
Management
Cultural – For both species once they are in your field, they are very difficult to control, especially in perennial orchards. The most important control technique is to prevent an infestation. Make sure your field is free of any bindweed or bittersweet before planting. If you see a small infestation of either, utilize resources to remove it before it becomes a large problem.
Bindweed3:
- Use mulch that is free of bindweed seeds or roots.
- Preventing seed-set.
- Clean tillage equipment between infested and un-infested areas.
Bittersweet:
- Don’t make bittersweet wreathes.
Physical – Physical weed control is especially challenging in perennial cropping systems because many of the physical weed control tools are not available to you. Here is what we know about physical weed control in both species. Some of the principles may be adaptable to your situation.
Bindweed:
- Try to suppress bindweed in the spring, consider:
- Planting a winter annual crop or cover crop that can shade bindweed in the spring.
- Early spring tillage.
- Repeated shallow tillage every 12-20 days.
- Target bindweed when the root reserves at a minimum:
- 12-28 inches tall
- 4-6 fully expanded leaves
- Tine weeders, rotary hoes, spyders, and rolling cultivators are ineffective bindweed can get caught in their axils.
- Organic mulch is completely ineffective.
- Black plastic mulch causes hedge bindweed to travel to holes near the base of a crop and quickly climb the crop.
Bittersweet2:
- Ultimately, you need to exhaust root system resources, which will take several years of consistent effort.
- Cut all vines, which will encourage regrowth and use more root resources.
- Cut multiples times throughout the year, over several growing seasons.
- Consider cutting vines and then treating regrowth with herbicide.
- Cutting first allows you to spray vegetative regrowth, which may be easier because it is not yet wrapped around the tree.
- Treat at least 8 weeks after cutting.
- Treat later in the season (after July 1st) to encourage herbicide translocation to the roots.
- Can also use the hack and squirt method but be cautious not to accidentally treat the crop.
- Work from the least affected area towards the most affected area to prevent the infestation from getting worse.
Chemical – Many of the products that control bindweed can be used in both apple and blueberry orchards. Bittersweet is more difficult to control than bindweed and only 2,4-D and glyphosate are somewhat effective. In both cases, be careful not to spray the crop with the herbicide or sever injury may occur. In most cases these herbicides will only suppress perennial vine growth. Combining chemical, physical, and cultural practices will help manage your weed growth. Always read the label and follow all application instructions.
| Herbicide Active Ingredient (example herbicide) | Crop | Herbicide type | Notes |
| Ammonium nonanoate (Axxe) | Apple, Blueberry | Non-selective, post-emergent | |
| Capric acid, Caprylic acid (Suppress EC) | Apple, Blueberry | Non-selective, post-emergent | OMRI certified |
| Carfentrazone-ethyl (Aim EC) | Apple, Blueberry | Selective, post-emergent | |
| Dazomet (Basamid G) | Apple, Blueberry | Soil fumigant | Restricted use pesticide |
| Glufosinate-ammonium (Rely 280) | Apple, Blueberry | Non-selective, post-emergent | |
| *Glyphosate, dimethylamine salt (Duramax) | Apple, Blueberry | Non-selective, post-emergent | |
| Halosulfuron-methyl (Sandea) | Apple, Blueberry | Selective, pre- and post-emergent | Only post-emergent applications target bindweed |
| Isoxaben (Trellis SC) | Apple, Blueberry | Selective, pre-emergent | |
| Sulfentrazone (Zone 4F) | Apple, Blueberry | Selective, pre-emergent | Label notes field bindweed only |
| *2,4-D, choline salt (Embed Extra) | Apple, Blueberry | Selective, post-emergent | |
| Oxyfluorfen & Penoxsulam (Pindar GT) | Apple | Selective, pre- and post-emergent | Label notes field bindweed only, for use when trees are dormant |
| Pyraflufen-ethyl (Venue) | Apple | Non-selective, post-emergent | Label notes field bindweed only |
| Saflufenacil (Treevix) | Apple | Burndown of broadleaf weeds, post-emergent | |
| Quinclorac (QuinStar 4L) | Blueberry | Selective pre- and post-emergent |
1Uva, RH, Neal JC, DiTomaso JM (1997) Weeds of the Northeast. Comstock Publishing Associates.
2Grover A, Jackson DR, Wurzbacher S, Templeton S (2020) Oriental Bittersweet. Penn State Extension Website. https://extension.psu.edu/oriental-bittersweet Accessed May 2024.
3Mohler CL, Teasdale JR, DiTommaso A (2021) Manage Weeds on Your Farm: A Guide to Ecological Strategies. SARE Outreach. https://www.sare.org/publications/manage-weeds-on-your-farm/bindweeds/