I recently had an email exchange with Ryan who lives in Pflugerville Texas, near Austin. He was concerned that mustard greens in his garden were being eaten by aphids and regardless of what measures he took, things were just getting worse. I thought our conversation might be of interest to many of you, as what Ryan experienced is so common.
Why are my mustard greens turning yellow?
“I planted mustard greens about a month ago and they were healthy and nice looking and now some leaves on the bottom and some on top are turning yellow. Someone said there were aphids on them and I sprayed them with some stuff. My question is can mustard greens get aphids on them? I know snails like them. And what causes the leaves to turn yellow? I have watered them once a week and we had rain for a few days so is it too much water or not enough?”
Yes, aphids may be the problem, but I doubt that water is. Are you using compost in your garden? What did you spray the greens with?
“Hi Todd here are some pics of the mustard greens. As you can see they have yellow leaves on them and they are getting beat up. I know there are a few snails I found but a lot I have killed as well. I did put topsoil in that spot and miracle grow dirt as well and I sprayed them with an organocide – a three in one garden spray – and if I can’t stop them from looking the way they do could I maybe replant some more as I love mustard greens.”
It appears that you have a number of insect problems. At this point, the mustard greens are a lost cause, so I would pull up all of the yellowed and otherwise damaged plants and bag them. Don’t compost them if you believe they’re loaded with aphids.
But if you’re overrun with insects your problem is more about HOW you’re growing your plants than the insects themselves.
Be careful which organic pesticides you use and read the labels before buying
You say that you used Organocide 3-in-1 spray. While the ingredients in that spray are indeed organic, it may have been unnecessary. It’s an oil-based spray and was probably too heavy for your greens in this case.
Regarding your soil product: Don’t take for granted any “organic” or “natural” labels – check the ingredients list. There are no legal rules on organic labeling for soil products, only food and pesticides, so chemicals or questionable ingredients are in many of these products, especially the ones made by the big chemical companies (of which Miracle-Gro is a prime offender). There are also no legal guidelines whatsoever for the “natural” label – it’s purely marketing.
Cultural controls are the best defense against aphids and other pests
For now, the best advice I can give you is this:
- Yank out all of the damaged and dying mustard greens – this season is over (it happens to all of us once in a while).
- Before planting your next batch of seeds or seedlings, work a lot of compost into your garden bed. Don’t buy any topsoil, it isn’t necessary.
- Plant your next bed of greens in a different location than where they are now to avoid possible insect infestation. This is called crop rotation.
- When the next growing cycle is underway, inspect your plants every day and at the first sign of insect damage, sprinkle diatomaceous earth around, underneath, and on top of the plants. This will kill any thrips, snails, slugs, and anything that flies, without impacting wildlife. But only use it when the soil is dry and when there’s no chance of moisture for 2-3 days because when it gets wet, DE cakes up and becomes useless. Also do whatever you can to invite birds into your garden, as they’ll eat whatever insects you miss. Between birds and DE, you need nothing else. Read about using diatomaceous earth in your garden
Once your soil is in balance, you won’t have insect problems, as the beneficial insects prey on the insects we don’t want, keeping everything in balance. Don’t panic and resort to chemicals.
“Thank you for the advice. I will pull the greens out then and I would like to plant more but I am out of room in the garden for the time being. What would be some good compost to buy as I buy mine usually from home depot or a little nursery by my house? Where can I buy that sprinkle stuff for the mustard greens to stop the pests from attacking them next time? And can buying ladybugs and releasing them in the garden help?”
If you’re out of room in the garden, let the bed rest (fallow), because if there’s nothing for the insects to eat, they’ll move on. For compost, but you don’t need anything special – plain old compost is fine as long as it’s from a reputable source. If you have the budget you might want to pay a little more for what’s called “soil builder”, which includes mychorrizal fungi and usually fish products or manures.
Try Diatomaceous Earth or Ladybugs to control insects
Diatomaceous Earth is available at most independent garden centers and online. Yes, Ladybugs can be very effective predators of invasive insects, but they will move out of your garden if they don’t find their favorite insects there. I’ve never bought any, but I always find a handful in my garden every year – Ladybugs will move in on their own if the conditions are right.
For now, load up the garden with compost and/or soil builder and let it go to work before your next planting. I’ll be honest – you won’t see instant results like you do with chemicals. It takes months to see results from soil builder and compost, but be patient, because once the garden soil gets balanced, your gardening will be much easier. Gardening teaches us nothing if not patience.