The Online Gardener's Handbook 2010
Chapter 4: Vegetables
Beans

Table of Contents

  1. Introduction
  2. Beans (not Broad, Fava or Windsor)
  3. Beans: Broad, Fava or Windsor
  4. Learn More

Introduction

In this chapter, a description of various bean pests will be provided along with suggested management options. These management options will not include the use of pesticides. Some biopesticides and certain reduced risk pesticides are still available to the homeowner for controlling weeds and pests in lawns and gardens. For more information, refer to Chapter 2 of this handbook and the Ministry of the Environment's website. For suggestions on managing specific weeds and pests, consult local horticulturalists, Master Gardeners or your local garden supply centre.

Beans (not Broad, Fava or Windsor)

Bean Rust

Bean rust is caused by a fungus and can be a very devastating disease that re-occurs yearly if not controlled. Numerous reddish-brown, circular, raised lesions up to 2 mm in diameter appear on leaves and sometimes pods. If leaves are severely infected, they will yellow, shrivel and drop. Infection is favoured in moderate temperatures when plants are moist for 10-18 hours. Pole beans are more susceptible than bush beans.

Management Options

Plant resistant varieties. Rotate crops. Remove and destroy all infected plant residues. Cut down and destroy vines and other crop refuse immediately after harvest and use new poles each year or thoroughly disinfect old ones. Follow proper watering practices and promote air circulation. In a small garden it may be necessary to stop growing beans for at least one growing season.

Leafhoppers

For information and descriptions, refer to the Leafhoppers section of Chapter 1.

Management Options

Wash nymphs (the more sedentary stages) off plants (especially leaf undersides) with a strong jet of water. Setting out yellow sticky traps near infested plants may trap some incoming adults, although it will also attract and trap beneficial insects (e.g. predators). Leafhoppers have a number of natural predators and parasites which can help keep populations in check.

Mexican Bean Beetle

The Mexican bean beetle is a dirty to coppery-yellow colour with 16 black dots (8 on each wing cover). It belongs to the same family as the ladybug and may be mistaken for it. The Mexican bean beetle overwinters in garden debris and appears on beans in late June. Later, groups of orange-yellow eggs will be seen on the underside of bean leaves. Soft, yellow larvae, 2mm long with black-tipped spines develop from the eggs. They feed on the underside of leaves, removing the green and leaving the veins.

Management Options

Do not mistakenly kill beneficial ladybugs. Hand pick and destroy adults and larvae. Crush egg masses when observed. Follow garden sanitation procedures, especially in the fall to prevent beetles overwintering in plant debris. Timing of planting to harvest an early crop before beetle feeding becomes significant may help. Some sources suggest that interplanting rows of beans with rows of potato or nasturtiums, or planting savory or marigold can help to repel this pest, however there is little hard evidence to support this.

Seed-corn Maggots

For information and management options, see the section on Corn pests.

White Mould

For descriptions and management information see White Mould section under Insects and Diseases Affecting Many Vegetables.

Beans: Broad, Fava or Windsor

Aphids

These beans are different from green and wax beans. They are not attacked by the same insects, but are often severely infested by aphids, which can lead to mosaic and yellow mosaic virus. For more information and management options see Aphids section under Insects and Diseases Affecting Many Vegetables.

Management Options

Plant broad beans as early as possible, or start them indoors and set out as transplants to avoid heavy aphid infestations.

Learn More

 


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 21 July 2005
Last Reviewed: 25 June 2010