The Rocket Guide to Pests & Diseases – Part 1: Leaves


We’ve put together a handy little 3 part guide for you to use this summer. So, if you have any growing pains in the veg patch, simply consult this guide to figure out what’s going on, and hopefully you’ll be able to save your plants before it’s too late! In part one we look at some common problems seen in the leaves of vegetable plants.

Identifying the problem

This is the first step to getting your plants back on the road to recovery. If you’ve spotted any discolouring, blemishes or signs of being eaten, then follow our flow chart to identify what the cause is. Once you’ve done that you can read on to see what you can do about the problem.

Click on the image below for a closer look:

leaf problems

Dealing with the problem

Once you’ve identified what the problem is, then it’s hopefully not too hard to get your plants back on track….


Aphids form in huge colonies and patrol the stems and leaves of plants leaving a sticky substance. You can usually get rid of them with a good jet of water from the garden hose. Do this a couple of times a day until they’re properly gone. It’s worth planting some companion plants (etageres and marigolds) to attract insects that eat aphids to keep your plants protected in the future.


Blight is a spore driven disease that commonly affects potatoes and tomatoes. It starts on the leaves and will spread to the stems and eventually the veg themselves, and it will spread rapidly from plant to plant.If you’ve got it, the best thing is to cut off any affected foliage asap and burn it to prevent further spreading. Blight can be avoided by leaving plenty of space between plants so that the air circulates better.


Have a really good look on the stems and undersides of leaves for any caterpillars or caterpillar eggs (they are tiny round eggs, usually white, yellow, green or black, and appear in little clusters.) Wipe any eggs off with kitchen paper, and pick any caterpillars off and pop them into a bucket to move to another area in the garden (the birds will be delighted!) Once you’re confident you’ve removed them all cover your plants with a layer of horticultural fleece to prevent butterflies from laying further eggs on your veg.


Chlorosis is a sign that your plants are lacking in some crucial nutrients which causes the leaves to turn yellow. You need to give your plants a liquid feed and it’s a good idea to add a mulch as well. A handful of wormcast fertiliser sprinkled around the base of the plant will also help to slowly release nutrients.


Earwigs bury into cosy little places (like sweetcorn cobs!) and will happily nibble through plants. If they’re affecting your crops we’d recommend putting pieces of bamboo or garden hose between the rows of plants. The earwigs are likely to hide in the hollows during the day, and you can empty them out before dusk.


These tiny little hoppers are not actually related to fleas, so don’t panic too much. They’re at their worst during dry spells and it can help to keep plants well watered. Once affected, you need to get rid of them (those sticky fly catcher strips work well or you can try spraying the plants with soapy water) and then pop a layer of horticultural fleece over the plants.


White/slivery blotches of powdery or downy mildew on the leaves of your plants, particularly courgettes, squashes, melons and cucumbers, is not a major problem if you deal with it quickly. It’s best to cut affected leaves off at the base of the stalk and burn them. Water the plants well to stop it from spreading, and try adding a mulch.


If pigeons have eaten your brassicas, then the chances are they won’t grow back. We’re sorry to be the ones to break it to you! But, it’s all part of building up a good glug of gardening wisdom for the future. Next time you plant brassicas, cover them with horticultural fleece or netting to keep pesky pigeons off!


Uh oh…if bunnies have been busy you might not have many crops left! If they are still salvageable, then get to work asap to build a rabbit proof fence surrounding your veg patch, or find some good wire mesh netting to cover raised beds with.


These tiny, spidery creatures are most likely to be a problem in dry greenhouses. Act quickly to avoid them doing real damage…spray plants with a light water mist sprayer early in the morning and again in the evening. Make sure you damp down the greenhouse (basically water the floor of the greenhouse early in the morning on hot days so that it adds moisture to the air later in the day) to prevent it from happening again.


This is most likely to affect fruit plants rather than veg. If you do see signs of rust, remove affected foliage asap and burn it to prevent it from spreading.Be sure to leave adequate spacing between plants to let the air circulate.


Arguably the most irritating pests in the garden, you need to be vigilant with these guys! Go out on a dusk patrol with a torch and a bucket (and a pair of gloves!) to pick them off and move them to a different part of the garden. It’s worth putting a barrier of grit/broken up eggshells around the base of plants, and make some slug traps by planting small containers of cheap beer in raised beds.

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