A Guide To Common Plant Diseases

It’s always disappointing when your carefully tended plants fall victim to a mystery ailment. But, as David Hall discovers, this needn’t result in its demise. First identify the complaint, then treat the plant to eliminate the cause, and hopefully the plant will return to healthy growth. Here is David's list of the commonest diseases and how they can be eradicated.

Created by David Hall on Friday, 21st of August, 2015.
Updated on Tuesday, 8th of May, 2018.


There are diseases specific to particular plants and varieties but here’s a selection of the more common complaints that affect the majority of plants at one time or another. If fungicide should be used I’ve recommended an organic version.

Bacterial Or Fungal Leaf Spot

Leaf spot is self explanatory, they merge into areas of dead tissue and will affect many different plants, causing the leaves to die. Rose growers know it as Black Spot. If caught early it is not fatal for the plant, remove the affected leaves, including any that have fallen on the ground, and burn. If appropriate, spray with a fungicide (dispersible sulphur) and hard prune in the autumn, destroying the cuttings.

Blight

A fungal disease causing yellowing leaves and black spots to appear. Blight spreads quickly amongst the foliage, so deal with this problem immediately, destroying the affected leaves and spraying with Bordeaux mixture.

Clubroot

Mostly affecting brassicas, this is a soil fungal infection that distorts and stunts roots, so inhibiting the plant’s growth. It is very difficult to control. There is no cure but preventative measures include improving drainage and adding lime to reduce acidity.

Downy Mildew

Plants in a cool and humid environment develop yellow / brown patches on their leaves and a mould on the underside that will turn black. This type of mildew will attack and eventually kill the plant. Remove and burn affected parts and ensure good air circulation. Mulch, hand water and avoid nitrogen rich fertiliser.

Grey Mould (Botrytis)

Thriving in damp air, this very common fungal condition presents itself as blemishes followed by grey mould on all parts of the plant. Rot may set in and badly infected stems will kill the plant. Destroy any infected parts both on the plant and ground, and then ensure that air circulation around the plant is improved and humidity reduced. Avoid over watering and nitrogen rich fertilizer.

Powdery Mildew

Leaves are covered with a grey coating usually on the upper surface, the plant’s vigour will be reduced but it should not be prove fatal. It will affect many plants growing in a dry soil. Remove and burn affected parts and spray with dispersible sulphur. Avoid overcrowding around the plant. Mulch, hand water and avoid nitrogen rich fertilizer.

Rust

A fungal infection when leaves and stems develop brightly coloured patches or pustules, causing them to wither and in some cases the plant to die. Again this is a disease that affects a wide range of plants. Remove the affected foliage and destroy,. Allow better air circulation and spray with dispersible sulphur. Rust may be an indication of other problems, so check over the plant.

Silver Leaf

Caused by a fungus that blocks water circulation in trees, the branches will eventually split and die. Look out for a leaves with a silvery appearance, although be careful that it isn’t, ‘false silver leaf’ caused by cold or drought. If it is Silver Leaf, cut off the branches and destroy.

Sooty Mould

This is a fungus and the name derives from its colour. It builds up on the secretions left by aphids. It may restrict growth but is not serious. If you control the aphids the sooty mould will disappear.

Related Articles

GardenSite Donates Prize To Grow Your Own Picnic

GardenSite Donates Prize To Grow Your Own Picnic

As part of a project designed to sow ideas, grow inspiration and cultivate futures, 300 London schools are growing their own picnic this summer and their reward could be a £500 voucher from GardenSite.

Author: David Coton

Written by David Coton.
Published on Friday, 25th of May, 2018.

Take Your Own Plant Cuttings

Take Your Own Plant Cuttings

Propagating by taking cuttings, whether from your own plants or ones you admire in neighbouring gardens, is a fantastic way of increasing the variety of plants in your own garden free of charge, and all you need are a sharp knife and patience.

Author: David Hall

Written by David Hall.
Published on Monday, 14th of May, 2018.

What To Do In The Garden In May

What To Do In The Garden In May

With the recent hot weather encouraging everyone out into the garden and the threat of frost disappearing during May, David Coton is in no doubt that this is going to be a busy month.

Author: David Coton

Written by David Coton.
Published on Monday, 30th of April, 2018.

What To Do In The Garden In December

What To Do In The Garden In December

Whether it's a bleak December or the more mild weather we are becoming used to, you can still spend useful time in the garden during the last month of the year. David Coton suggests some garden jobs that can occupy the short days.

Author: David Coton

Written by David Coton.
Published on Monday, 20th of November, 2017.

comments powered by Disqus

Author

David Hall David Hall

View Profile

RSS

View RSS Feed

Follow Us!

Recent Articles

What To Do In The Garden In November

What To Do In The Garden In November

David Coton suggests that there are plenty of gardening jobs that need to be done in November, from why you shouldn't throw away your fallen leaves to how to take care of your vegetable patch.

Author: David Coton

Written by David Coton.
Published on Friday, 27th of October, 2017.

New Barlow Tyrie Outdoor Furniture To Celebrate Centenary

New Barlow Tyrie Outdoor Furniture To Celebrate Centenary

In these uncertain times it's reassuring to know that Barlow Tyrie have been designing and manufacturing top quality teak furniture for nearly a century, and they have announced several new ranges to coincide with their one hundredth birthday.

Author: David Coton

Written by David Coton.
Published on Monday, 14th of October, 2019.

Review of Evika G1 Greenhouses

Review of Evika G1 Greenhouses

I had never heard of Evika Greenhouses but when I walked into our annual Garden & Leisure Exhibition 2019 (GLEE) it was the only product I really saw. A brand new greenhouse brand is always going to get my attention but the sense that this was not only new, but different, kept my focus.

Author: Robert Hall

Written by Robert Hall.
Published on Thursday, 12th of September, 2019.

Planned TV Gardening Programmes 2019

Planned TV Gardening Programmes 2019

There's no doubt that television provides gardeners with inspiration, sound advice and good ideas, that's why we're all looking forward to new programmes and the return of old favourites during 2019.

Author: David Coton

Written by David Coton.
Published on Tuesday, 13th of February, 2018.