Types of Garden Diseases and Disorders

Fight off common garden diseases with this guide for identifying problems before they worsen.

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©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2011, Dorling Kindersley Limited

©2012, Dorling Kindersley Limited


A fluffy, gray mold (or whitish spots on tomatoes) that enters plants through wounds or flowers. Remove dead and infected plant material to reduce risk of infection. Find out more about common plant diseases here. And follow these tips to prevent plant diseases.

Types of Garden Diseases and Disorders

Just like people, strong, healthy plants are susceptible to disease and infection. Here's how to get to the root of common garden problems. The coral spot pictured here is commonly seen on dead twigs of trees and shrubs. In damp weather, small pink or red eruptions appear on infected bark. Cut out diseased areas promptly.

Potato and Tomato Blight

Brown patches on leaves, fruits, and tubers, caused by a fungus that thrives in warm, wet weather. Grow resistant varieties or spray with copper-based fungicide.


Fungus that causes brown, slimy rot with fluffy, white growth, predominantly on stems and fruits of various vegetables. Remove and burn or discard affected plants.

Magnesium Deficiency

Older leaves of various vegetables show yellowing between veins, especially in acidic soil or after heavy rains. Apply Epsom salts to the soil or as a foliar spray.


This soil-borne slime mold infects brassicas, causing swollen roots, wilting foliage, and even death. Ensure good drainage, add lime to acidic soil, and choose resistant varieties.

Blossom End Rot

Dry conditions affect calcium uptake, which causes sunken, black patches at the tips of tomatoes and sweet peppers. Correct with adequate, regular watering.

Powdery Mildew

A wide range of crops are affected by these fungi, causing powdery white growth on leaves in dry soil conditions. Water the soil well, but not over the leaves.

Onion White Rot

This fungus persists in the soil for up to seven years and causes fluffy white growth on bulbs and roots and yellowing of leaves. Remove and burn infected plants.


Orange or brown spots appear on the leaves and stems of various vegetable crops, particularly in damp weather. Remove infected leaves and grow resistant varieties.

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