Problem Area - Plant Diseases

The focus of these posts are Fungal Diseases and these have visible symptoms such as -
Leaves producing spots, wilting & curled leaves, dieback, enlargements (galls) and stunted / dead plants. Some fungi's produce other visible signs such as rusts, mildew & sooty moulds.

This is a very common disease, especially on plants in a Greenhouse at this time of year as it favours conditions of low temperatures, high humidity and poor ventilation.
This disease produces fuzzy grey mould and can be expected at any time of year on a wide range of plants.

Here are a few things you can look out for ...

- As the picture shows above there is a formation of grey fuzzy mould, as soon as you spot this on any material remove it immediately.

- When this disease is established it can cause damage to developing fruit on plants such as Tomatoes & Strawberries causing them to rot and fall from the plant.

- On plants grown outside the buds and flowers may be have shrivelled and died.

- Small black seed like structures form in the infected material.

- On Soft Fruit e.g. Gooseberries the grey mould isn't as evident and the infection kills the branches.

Here are a few things you can do to help prevent this ...

- When trimming leaf stalks and removing material make sure you do it cleanly.
Botrytis can gain hold easily on badly trimmed material.

- Remove affected material immediately to prevent the disease spreading. Don't leave any of this material hanging around, dispose of straight away. Check your plants daily.

- Regular dead-heading of flowering plants.

- Good ventilation (i.e. opening GH doors and windows) to allow good air flow and don't overcrowd plants.

- Careful watering ... avoid getting any water on the plant and ideally water in the morning so that it has dried by nightfall.

This is a very common disease found on edible and ornamental garden plants.
You may have especially noticed it on your Sweet Peas and Roses!
Photo from Google

Here are a few things you can look out for ...

- Powdery Mildew appears in early May as irregular white mealy or felt - like patches on the surface of young leaves, stems and flower buds. This increases during Summer and will remain active into Autumn if the weather is mild. Dry weather and heavy dew on a morning can encourage the infection. If you have Roses growing on dry sites against a sunny wall they are more liable to be attacked.

- Younger leaves curl and distort and may develop a discolouration i.e turning purple or yellow.

- If your plants are badly affected the foliage will wither and fall prematurely leading to die back of the plant.

Here are a few things you can do to help prevent this ...

- Incorporate organic matter annually to the ground and giving the surface of your borders a mulch reduces moisture loss from the soil, this will help the resistance to infection.

- Ensure that you give your plants adequate watering.

- Pruning your plants will remove most of the over - wintering infections on young shoots and the tops of stems, reducing the chances of the disease. If your plant is affected make sure you remove and dispose of any affected material right away.

- Avoid excessive use of nitrogenous fertilisers, these produce soft growth which is more vulnerable to attack and ensure that adequate feeds of Potash is given to your plants.

- Try growing plants that are advertised as being resistant to Powdery Mildew.

Chemical control can be gained by using a contact fungicide, spraying periodically. If you choose to use one make sure you follow the instructions exactly and avoid using when pollinators are around. 

Even to non gardeners this disease is pretty well known!
This is the most serious disease of Roses which infects the leaves and greatly affects the plant's vigour from Spring onwards. This disease freely spreads if left untreated from the diseased material to healthy leaves all through the Summer, especially in damp weather.
Photo from RHS website

Here are a few things you can look out for ...

- As the picture shows above infected leaves often turn yellow and fall off by early Summer. This also affects the ripening of flower buds. If your plant has a serious loss of vigour this can affect the whole bush for the following year.

- Dark irregular spots may appear on the leaf stalks and stems, especially on soft growth.

Here are a few things you can do to help prevent this ...

- Remove affected material from the plant as soon as it is spotted and keep checking your plants for any signs throughout the season. All affected material on the plant and any that has fallen to the ground should be collected up and burnt right away.

- Choose Roses that are resistant varieties to plant in your garden, such as Rosa Rugosa.

- Mulching Roses and giving them a feed in Spring can be beneficial against preventing the disease.

Chemical Control can be used with products such as Rose Clear. Spray at the first sight and repeat as per the instructions throughout the season. Try to use these products when pollinators are least likely to be about, example before 8am or after 8pm.

Damping off is an extremely common problem during the upcoming weeks as gardeners start their seed sowings! Damping off can affect most seedlings and is caused by several soil-borne Fungis.
Photo from Google

Here are a few things you can look out for ...

- Attacks young seedlings, specially those grown under glass. This is particularly common if the seedlings are in areas of high humidity and poor ventilation, along with thick amounts of sowings.

- Failure of seeds germinating.

- Seedlings collapse, often white fungal growth is visable.

Here are a few things you can do to help prevent this ...

- Ensure seed sowing compost is fresh and of a good quality. Also make sure that any seed trays or pots are cleaned before use and hasn't been used with sowings that have succumbed to damping off before.

- Sow your seeds thinly.

- Use mains water when possible to water seedlings and do not over water.

- Enusre seedlings have good ventilation to reduce humidity.

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