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The Greenfly saga

How do you remove greenfly

So far we've been lucky.  In 8 years of growing chillies commercially, we've only had one severe greenfly outbreak... and this was due to some plants we purchased from a "professional" grower.   We had to isolate the infected plants in a separate area before we put them back into the main tunnels as not to spread the problem.

So what are they

There are many species of Aphids and most work in the same way. They vary in colour from green, yellow, white, pink or brown. They measure between 2-5mm long.

Aphids attack the plants by inserting their mouth parts into the tissue of the leaf and sucking out the sap.  Excess sugars and water are excreted as a sticky substance called Honeydew and this causes a black mould. This black mould is unsightly but worse than that, it can interfere with the plant’s ability to make 
sugars by photosynthesis .
Aphids move from plant to plant, infecting each one whilst feeding on the sap.
They can reproduce at a phenomenal rate especially if there is a good food supply, warm humid conditions and are left alone by predators and us humans!
Signs of aphid infestation are distorted leaves and shoot tips.

We would encourage all growers NOT to use those horrible yellow sticky traps which although may catch the nasty critters, will also trap and kill the good-guys such as ladybirds, lacewings and hoverflies.    We also don't recommend using commercial pesticides as these will kill all the bugs in your greenhouse.   As a rule we do not use ANY form of non organic pesticide or herbicide.

Dealing with Aphids

A list of things you can try.  

We use   1, 4 and 10

1) Companion planting - Planting Hyssop, Dill, Lavender, Nettles, Calendula, Thyme etc.. next to your chilli plants will encourage natural predators into your greenhouse.  Garlic grown amongst your chilli plants  will deter aphids.

2) Squashing - Not something we do but an effective method. Just remove them from the stems and top & undersides of leaves from your plants and squish the little blighters.

3) Barriers - It is possible to get insect proof mesh to protect your plants. However if you can attract the good predators, you shouldn't need it. 

4) Natural Predators - Many birds especially Blue Tits and Sparrows will eat masses of aphids so if you have an plant which is usually kept on a windowsill, try putting it in a warm sheltered place outside for a few days.  Other good predators include Ladybirds, Lacewings, Hoverfly and earwigs.  Ants on the other hand are not good news.  Whilst ants wont damage your plants, they will protect the aphids as Honeydew is one of their main food supplies. A build up of ants around your plants is often a sign of aphid numbers building up.

5) Biological controls - Great for controlling aphids in confined spaces such as a polytunnel or greenhouse. There are two main types which are both midges.  If you have large numbers of greenfly tryAphidolytes whilst Aphidius is a small parasite which is good for hunting smaller amounts of aphids. 

There are lots of sources for Biological controls - try
They come in a tube are larvae which you position by infected plants.  Take the lid off and they will come out and scoff the aphids.  A Lacewing larvae will eat as many as 300 aphids and each adult Ladybird will eat as many as 5000, so well worth encouraging to your polytunnel.

You can also collect Ladybirds from stinging nettle plants and then release them in your greenhouse. Once you have the good predators in your garden, encourage them to stay by companion planting.  You can also get Ladybird houses which is a good way of making sure they stay in your garden!

Ladybird larvae look very unlike the adults and can be mistaken for a pest. They are about 1/2 cm long and have dark grey, segmented bodies with yellow spots.. Make sure you know what they look like so you don’t accidentally kill them.  

6) Organic Sprays -  ie SB Invigorator - Controls aphids and used regularly will reduce fungal diseases such as mildew PLUS it contains a foliar feed to help plants recover from pest attack. SB Invigorator is not only highly effective, but it is also biodegradable and non -toxic ,which means it can be used in the garden, conservatory or in the greenhouse and on edible plants too - pick and eat straightway. It is suitable for use throughout the year and brilliant at clearing heavy infestations BEFORE introducing a natural control.

7) Smoke candles - Fumigating a greenhouse at the end of the season with a sulphur candle has been the traditional way of clearing pests.  However we recommend Natural Garlic Candles instead.. They are used in the same way as a sulphur candle i.e. simply place in your greenhouse, light the fuse and leave overnight. HOWEVER, unlike sulphur candles you do NOT need to remove the plants before using and they are safe to use in aluminium greenhouses and polytunnels. Garlic candles will not taint any fruit and / or vegetables.

8) Spray Soaps - Mixing a small amount of washing up liquid with water and spraying this onto the leaves of your chilli plants is a good way of reducing aphid numbers. The soapy water gums up their suckers. However it is difficult to get the balance. Too much washing up liquid will harm your plants.

9) Garlic - Another traditional method. Crush garlic cloves and mix with soapy water to create a garlic spray which deters aphids.

10)  Rhubarb leaves - boil some rhubarb leaves in water in an old saucepan (not one you are using for food). Allow to cool.  The oxalic acid in the rhubarb leaves is a good deterrent for aphids.   This method is often used on roses but works fine on your chilli plants aswell.  Don't use on chilli plants which are fruiting though. The big disadvantage is that the leaves are toxic.  A solution is to use Spinach leaves instead of rhubarb leaves. 

If you have all your chilli plants inside, make sure to check your other house plants.  
You don't want the little blighters coming back!

Feedback from customers : 

Just wanted to say a quick 'Thank you' for your recent advice regarding our sudden infestation of Aphids. We are very pleased to tell you that the garlic water method has worked a treat and the affected plants are now on their way to a full recovery. Needless to say we will be keeping a large stock of fresh garlic in the larder from now on.
- Mark & Tracy McGarry, Nottingham

Cheers for the great advise - re: aphids.  Both the nettle feed and garlic spray have really helped by chillies. They have recovered!
- Phil Thompson, Cardiff.

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Tim Parsons - 26/07/2016

We met you at Chagford show last year and the rhubarb leaves really work!