Lentil Weed Control
Since lentil is a short crop with a thin crop canopy, weed competition can greatly reduce yields. Weed control is the critical step in preserving yield potential. Weeds such as wild tomato or round-leaf mallow, which rarely reduce yield in competitive cereal stands, can be problem weeds in thin lentil crops. Apart from reducing yields, these low-lying weeds will interfere with harvest.
The Year Before Lentil Production
A lentil weed control program starts the year before planting, with proper field selection and management.
- fields should receive either pre- or post-harvest glyphosate treatments
- avoid late-fall application of 2,4-D, MCPA, Banvel® or Rustler® (which contains dicamba) for the control of winter annuals, or early spring application of these herbicides for pre-seeding weed control (these applications can cause crop injury, especially under dry, cool conditions)
- only fall application of trifluralin products such as Advance®, Rival®, Bonanza 10G® or Treflan® is recommended (Sencor® can be used in a fall-applied tank mix with liquid Treflan®)
- spring application of these products can result in crop injury, reduced seedling vigor and uneven plant stands due to a dried-out seed bed
- even with fall herbicide applications, it’s important that the crop emerge quickly to avoid injury – deep seeding and cold or dry soil conditions can aggravate crop injury problems associated with trifluralin products
The Year of Lentil Production
In the year of production, weed control starts early with a pre-seeding application of glyphosate, provided weeds are actively growing. Effective use of glyphosate can compensate for the limited number of post-emergent herbicides. Pre-seeding tillage can also be used, but this operation can reduce seedbed moisture.
Lentil crops have few post-emergent herbicide options. Most grassy herbicides cause little or no crop damage although Hoe-Grass® (diclofop methyl) will cause leaf cupping and leaf burn if applied during hot, humid weather. Check the Alberta Blue Book for up-to-date crop protection products.
- Broadleaf herbicides generally cause more damage
- Sencor® (metribuzen) should not be applied to lentil seeded less than 2 in. (5 cm) deep or on soil with less than 4 per cent organic matter content (only Sencor® tolerant varieties – check green lentil variety tolerance)
- full rates of Sencor® applied during hot weather will result in leaf burn
- to avoid crop injury, Sencor® should only be applied to lentil in the second to fifth node growth stage – late applications (after the fifth node) will severely damage the crop and are not recommended
- the safest and most effective strategy is often a split application: half of the full Sencor® rate at the second node stage followed by another half rate 10 to 14 days later
For detailed information on applying herbicides to lentil, as well as information of the weeds controlled, consult Agdex 606-1, Crop Protection.