Underplanting the Orange Grove

Hello, how are you doing out there after the excesses of the festive season? If you’re at the stage where finishing off that last box of chocolates has started to feel like something to cross off the to-do list, you’re probably ready for a bit of exercise. Let’s go for a virtual walk down to the orange grove and I’ll show you what Deborah and I have been planting.

Comfrey flower

Look a comfrey flower, right on the edge of the grove.

As any citrus pest worth her salt knows, thirty-one orange trees planted in close proximity constitute an invitation to party hard. Ergo, on moving onto the farmlet we were greeted with evidence of the extensive carousing of Northland aphids. The entire grove was disfigured by <use your ominous voice> Black. Sooty. Mould. Yes, it really is a thing. It’s a fungus that grows on ‘honeydew’.

Honeydew is what entomologists call the excrement of aphids and scale beetles. Haha! Perhaps equestrians should start calling horse excrement ‘meadow-dew’. That would certainly put a new spin on poo pick-up — ‘I say friends, let’s pop out to the paddock and gather us some fresh meadow-dew shall we?’.



Anyway, I digress. Black sooty mould is a sign that you have a nasty aphid or scale beetle infestation and those little critters are sucking the sap out of your trees. The mould is less damaging than the insect pests, but as it grows and covers the leaf surfaces it reduces the tree’s ability to photosynthesise. A malnourished tree is a low health tree, and low health trees are more susceptible to attack by varmints of the sternorrhyncha suborder. Cue a downward spiral of happy pests and sad trees.

Bishop dropwort

Parsley dropwort, known locally as carrot weed.

One way to quash aphid parties is to grow plants in your orchard that encourage predator insects. Ladybirds, lacewings and praying mantises (yup, I checked, and that really is the plural of mantis) suck the juices out of those sternorrhynchas like vampires at a nightclub.

If you choose carefully your underplanting species can also enhance soil fertility, suppress grass (grass isn’t ideal in a citrus orchard because it competes with the trees for food), and reduce the need for watering by acting as a living mulch. Oh, and they look pretty don’t you think?



Luckily for us Deborah knew about the Manukau Institute of Technology plant nursery (highly recommended), and before Christmas she stocked up on comfrey and nasturtiums at $1 per plant. Earlier in the year we had transplanted some borage seedlings from the Kragbol’s Auckland garden, and some comfrey from the garden at our old house.

Queen Anne's Lace

Queen Anne’s Lace

Our underplanting has a long way to go. Although the individual plants are thriving, at the moment the orange grove undergrowth still sports way more out-of-control grass and tradescantia than it does swathes of pretty and beneficial herbs. Never mind, there is another wave of propagating and planting on the list for autumn. With luck we’ll get some decent rain around then which will give our next batch of seedlings a good start.

Anyway, although it is very early days, I’m pleased to report that I’ve noticed quite a number of Steelblue Ladybirds in the grove recently.

Steelblue Ladybird, hard at work hunting aphids. What is super-cool is that if you look very carefully at her metallic sheen you can just make out my reflection as I take the photograph.

And so far no Black Sooty Mould to be seen.



    • I am unable to decipher this comment. Any of The Readership know what Chocolate Bear is referring to?

  1. No idea. My book shows a lot of the spotted sort, steelblue, yellow-shouldered… but they all seem to LOVE aphids. Can eat about 100 a day – do you have enough pests for them?

    • Wonder what they eat when they run out of aphids and scale. Do they just keel over from malnutrition, or swap to another food source? I have seen some aphids, but not many. Perhaps we have a happy balance for now.

  2. Good on you planting g borage with its pretty blue flowers. Have just tried throwing a few plus lemon
    balm and mint in a fruit smoothie. Yummie. If you need more we have a great excess of seedlings and they are very prickly when mature. ……. Why is everything going to seed so early this season? Bring on the rain. Shall we dance ?……

    • Definitely we should all dance. Borage seedlings will be gratefully received. We’re hoping ours will seed prolifically, they’ve yet to flower though. Smoothie sounds great.x

  3. Oooh! Thanks to your marvelously educational blog I just identified a steelblue ladybird in my own garden. So pretty and, I now know, functional 💜

    • We are all learning together! I didn’t know the name of the metallic ladybird either until I looked it up. Gotta love Google.

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