Pest Management

Weed Control

Early-season weed control is important for faba beans, as they are relatively poor competitors. Reduced plant emergence under dry conditions, for example, can further reduce competitive ability of the crop.

Tips on weed control in faba beans:

  • Use pre-plant herbicides to improve early-season competition and avoid the need for broadleaf weed control in-crop.
  • Aim to control perennial weeds in the fall.
  • Consult the Guide to Field Crop Protection, product labels and manufacturer representatives for information on the best herbicide options, risk of herbicide carryover and pre-harvest intervals.

Quick links: Weed Seedling Identification Guide and 2020 Field Crop Protection Guide and addendums.


The main disease pests of faba beans include chocolate spot (Botrytis cinerea or B. fabae) and Ascochyta fabae. Higher incidence of these and other diseases can be expected under irrigation. Like soybeans and other pulse crops, faba beans are susceptible to the root rot complex, including Fusarium spp., Pythium spp. and Rhizoctonia solani. According to a 2009 survey conducted by Dr. Robert Conner at AAFC, all three root diseases were present in faba bean crops, but Fusarium avenaceum was the most common.5 No crops were severely affected by F. avenaceum at the time, but inoculum can persist in crop residue for several years, especially with a wide range of host crops. In the same study, fungicide seed treatment improved seedling emergence and yield.

Below is a list of foliar diseases to scout for in faba beans. However, not all diseases will occur at economical levels and not all can be controlled by foliar fungicides.

·        Chocolate spot (Botrytis cinerea or B. fabae) ·        Ascochyta blight (Ascochyta fabae)
·        Anthracnose ·        Bean yellow mosaic virus (BYMV)
·        Sclerotinia ·        Alternaria leaf spot
·        Rust ·        Powdery mildew



Insect pests to watch for in Manitoba-grown faba beans include cutworms, lygus bugs, pea aphids, bertha armyworms, grasshoppers and blister beetles. Scout for severed plant tissue caused by cutworms early in the season. Note that insecticide seed treatments do not provide protection against cutworms and faba seedlings can re-grow after they are damaged.

Scout for lygus bugs starting in mid-June. Lygus bugs pierce the pod and cause damage to the seed coat, appearing as a brown spot on the seed. This direct damage to the seed can cause downgrading. As lygus bugs and bertha armyworms are also pests of canola, be vigilant of pest pressure if these two crops are close in rotation.

Less is known about the extent of aphid damage to fabas in Manitoba, but damage will appear as brown spotting on the undersides of leaves. Grasshopper and bertha armyworm forecasts are also available from Manitoba Agriculture each season.