My tomatoes were a disaster last summer. Tomato pests ruined them. It normally doesn’t take much to get rid of insect pests and keep the plants healthy. But tomato/potato psyllids aren’t your normal, run-of the-mill pests like aphids. Oh no, these insects are killers – tomato and potato plant killers.
We all want healthy, trouble-free plants that carry loads of well-formed, tasty tomatoes. That’s the home gardener’s dream. But, based on my recent experience, I know that this dream requires some determined input from the gardener if it is to come true. Your plants will look like the picture on the right (not my plant but very similar) if you don’t tackle the problem of tomato pests right from the time the plants go into the ground.
What Causes the Devastation?
Insects are elusive pests. One season their numbers can be low; perhaps a cold winter killed off more than usual. Weather and other factors being in your favour, you’ll have a crop to be proud of. By the next season, however, their numbers have returned to full strength. Now, you need to be alert if you want to keep bugs off tomato plants: unless you are prepared, your precious young plants will be waiting for the attack, unprotected and vulnerable. If that happens, your crop is doomed to failure.
You’re unaware of trouble until you see some of the leaves developing a purple colour. Or they might turn yellow and curl at the edges. Perhaps the growth of the plant slows down and fruit are slow to grow. It’s not the weather or the temperature. It’s not too much or too little fertiliser. It has nothing to do with watering. It’s nothing you did: in fact it’s something you have not done that’s at fault. Like me last summer, you have failed to protect your plants against the insect enemy, and…
I’ll tell you what has happened: the tomato/potato psyllid onslaught has struck.
NB: If Tomato Psyllids aren’t a problem in your area, the advice in this article applies to other sucking or chewing insect pests as well
What Are Tomato/Potato Psyllids?
The word “psyllid” looks friendly to me, something like “sylph” or a reminder of the ballet “Les Sylphides“, where sylphs dance in the moonlight. But beautiful fairy tale creatures these are not. They are small insects, about the size of an aphid. They have a liking for tomatoes, potatoes and other members of the potato (Solanaceae) family – including capsicum (peppers) aubergine (eggplant) and tamarillos. Other hosts plants include the weed black nightshade (very common in my area), Physalis spp such as cape gooseberry, morning glory, and Convolvulus arvensis (field bindweed).
Tomato/potato psyllids are sap suckers like aphids. But, when they suck they inject a bacterium, Liberibacter solanacearum, which, together with the sap sucking, causes devasting damage and loss to crops. I came across these psyllids several years ago when their uninvited, unwelcome arrival caught New Zealand home gardeners unawares.
These psyllids will also ruin your potato crop as well as your tomatoes if you live in New Zealand or a few other countries. My research suggests that they are less of a disaster in North America, where they originated. That means that they can still cause damage, only not as much.
The adult psyllid looks rather like a very small cicada, with clear wings and banded body. You would need a magnifying glass to see any detail because it is only 1/8 inch (around 3 mm) long. The adult female lays orange-yellow eggs which are raised from the leaf by a hair-like thread. After 4 -15 days small nymphs hatch. These look like scale with short legs. They become adults after 2 – 3 weeks. One female can lay thousands of eggs.
The small size of psyllids allows them to occupy your plants without being noticed. By the time you realise that something is wrong, it can be too late to save the plants. In warmer areas they can arrive as early as mid-spring, varying to early summer in cooler districts.
How To Detect Their Presence
- Hang sticky yellow traps near the tops of the tomato plants and watch for psyllids. These will also trap whitefly and some other insects so it could be difficult to recognise psyllids.
- Watch for psyllid sugar, a crystalline substance that forms from the sap excreted by adults and nymphs. You may find that some of it has attracted black sooty mould (mold).
- Stunted growth.
- Leaves turning yellow and curling – psyllid yellows – and purple coloured plant tops,
- Flowers may fall off trusses of infected plants. Fruit that develops is often small and/or misshapen.
How to Stop The Tomato Pests’ Attack
You’ll have realised by now that psyllids are nasty little pests that can do a huge amount of damage to your tomatoes. They can, in fact ruin the crop. Can you imagine how commercial growers might feel?
You, as organic home gardeners will be familiar with the practice of controlling tomato pests without the use of toxic sprays. If you don’t, you need to learn fast because these invading tomato pests take no prisoners. Anyway, I have a list of some suggestions to help you protect or save your crop. These ways aren’t foolproof – the perfect safeguard against psyllids and other plant-destroying bugs hasn’t yet been discovered or invented.
- Be on the lookout for psyllid attacks. Keep your plants well fed and adequately watered, then inspect them weekly. Take a magnifying glass with you if possible.
- Keep your garden clear of host weeds, such as black nightshade.
- Encourage beneficial bugs to your garden by growing plants they feed on.
- Carefully examine any host plants you buy or are given, e.g tomato seedlings, cape gooseberry plants.
- Remove and destroy as many infested leaves as possible. This can lessen the risk of psyllids spreading further.
- Spray the plants with Neem oil, following the directions on the container.
- Use diatomaceous earth, which is an effective natural insecticide. It can be puffed on to a plant surface using a powder duster similar the one shown below (right)
- Spray with pyrethrum spray, which most authorities class as organic. You can make your own or find a suitable commercial variety. However, avoid those with piperonyl butoxide as one of the ingredients – it is a cancer-causing suspect.
- Be extra vigilant with young plants, which are more susceptible to pests than more mature plants. Remove and destroy badly infested plants. Even if they produce ripe fruit, the quality and flavour of it will be inferior.
I’m not suggesting that you use all these products. The list gives you an option. For instance, if you use diatomaceous earth you may not need the sprays. I haven’t used it for that purpose and don’t know how effective it is.Alternatively, you could use pyrethrum spray instead of anything else you’ve been using. Or spray with it and then follow up a few days later with Neem Oil.
In New Zealand, gardeners can buy Neem granules, broken-down Neem bark. See if they are available where you live. I’ve used the for years – a lazy gardener’s way to hit the bugs. When water is applied to the Neem granules, some of the product soaks into the soil and is taken up by the roots of the plants. It appears to act as a systematic insecticide, attacking the bugs when they chew or suck on a leaf. Rest assured, though, that the leaves are safe for us to eat.
Keeping tomato pests at bay is normally not too difficult. But with the tomato/potato psyllid, you need extra vigilance and fast action. This insect is capable of ruining your tomato crop, and it will do the same with your potatoes. Organic gardeners can use Neem oil, diatomaceous earth or Pyrethrum spray once you notice their presence. However, prevention is your best defence. Keep alert, especially from mid-spring to early summer when your plants are still immature and more vulnerable. Remove affected leaves and treat the plants as suggested.
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(1) Psyllid infestation: Whitney Cranshaw, Colorado State University, Bugwood.org
(2) Tomato/Potato Psyllid – adult: Whitney Cranshaw, Colorado State University, Bugwood.org
(3) Psyllid nymphs: Alton N. Sparks, Jr., University of Georgia, Bugwood.org
(4) Psyllids at all stages: Whitney Cranshaw, Colorado State University, Bugwood.org