All this wet weather we’ve had has provided an opportunity for aphids to get a foothold in many local gardens – mine included. I have found black aphids on a sunflower and cabbage aphids on – well – my cabbages.
As there is often a mid-summer push of aphids, I thought it was time to remind you of the care that needs to be taken. And that care – might be to do nothing!
Yes, you heard me. In a totally organic garden where plants are appropriately placed and provided no “unnatural” fertilizer, plant growth will keep up with pest growth and plant susceptibility will be low. Here in BC, the aphid parasitizing wasp Aphidius with it’s many different types emerge almost as early in the spring as the aphids. So, one day you see an aphid, the next day you see an aphid mummy! The aphid mummy, is the aphidius inside the dead aphid, about to emerge – so technically it is a parasitoid – since its host must die for it to complete its lifecycle.
(Adult aphidius on Kale)
Here’s the trick that might mean you need to do nothing – you must never spray anything! Obviously there is no point in spraying a commercial pesticide in your garden, but dubious marketing and crazy online people suggest that some off-the-shelf spray or homemade concoction is good for aphid control and is still considered organic. Sure, it might work, but while it harms your targeted pest, it surely harms your helpful predators who are almost always more susceptible to chemical harm. And, in no way, should it be considered organic. Remember “Chemical” doesn’t mean “manmade”, there is nicotine in your egg plant, and cyanid in your peach. Take aphidoletes aphidimyza for example. On plants washed with “Safer’s Soap,” aphidoletes will never again set foot. So, you can wash your aphids off for a short term fix, but be prepared to spray it again and again since your aphids will be predator free.
In fact, any soap or detergent is problematic. They can wash away pests, but will also strip leaves of the natural oils that protect it from sunlight, mold, pests…etc. However – if you have a market value on your product and need to sell it, by all means, soap it down and get it to market.
So, take a look at what an aphid infestation looks like in a totally unsprayed garden:
You will see the enormous number of mummified aphids (the tan coloured oblong balls), and in the photo previous you will also see the adult aphidius (little black wasps) sitting on the cabbage leaves. This is a prime example of nature at work. I did nothing to encourage aphidius other than provide the plants that provide the aphids.
The black aphids on sunflower are a different story – no aphidius here. So, this is where action is required. I’m going the traditional route of applying aphidoletes aphidimyza to my yard. But, I won’t put it near the sunflower. Instead, I will put it with the cabbages where I know the aphids are still in higher numbers. Now, when I apply 250 adults, but put them into a situation where they can feed and multiply, I can have several hundred times that amount in a few weeks. Also, I want to eat the kales and cabbages and brussels, so aphid free is good for me (my new tagline).
The sunflower can take a beating and still produce a beautiful flower and food for bugs, so I’m in no rush to get rid of the black aphid. Furthermore – my cabbages are near nasturtiums which are magnets for black aphids, so I expect to fight that battle there.
I have hung an “Aphidoletes Max – Hanging Vial” from Applied BioNomics on a kale. This will provide a slow release of aphidoletes into the garden.
I also took a regular tray of 1000 aphidoletes and put it on the ground under a cabbage leaf (out of the rain). This is more aphidoletes than I need (much more), but since they can over-winter, I figured I am giving them a home. The only risk with too many good bugs is that they run out of food and move on.
This is not likely with aphidoletes, since they will eat aphids at other lifecycles than the aphidius is parasitizing, and they will eat whitefly and other pests they come across.
You can buy aphidius commercially…..but……aphidius have many different varieties. Many of which parasitize only one type of aphid. Of course, they can adapt, but what you get when you buy them is just one kind (like Colemani) and you don’t know what it is reared on. If it is reared on a small aphid, it may have adapted, and is no longer able to parasitize larger aphids (This has actually happened to some of the large companies). Others sought to rear aphidius on alternative food sources in buckets. What you get when you buy them is aphidius that were selected for ones that fly poorly and are lazy feeders. It is likely best just to let the natural ones arrive.
You can buy ladybugs commercially ….. but ….. ladybugs are primarily harvested from their native habitats. The collection is unsustainable, and has caused foreign beetles to move in to traditional lady bug territories. Plus, they are refrigerated and come to you with reduced abilities to eat, reproduce and search. And, they don’t “control” aphids, but they do eat them. They eat a few, lay their eggs and move on. If you want aphid control, you need something that will rid the plants of aphids…..not ladybugs…. besides, they will show up on their own.
Some tips on Scouting for aphids:
Do not forget….. ants are your enemies. If you see ants running up a sunflower, follow them. They will often lead you to aphids. The ants will fight off the good, aphid-killing bugs in order to protect the aphid so the ants can harvest their honeydew secretions. If you throw enough good bugs at them, the ants will simply carry the juiciest aphids away to establish another farm elsewhere. Should you trap the ants in your garden? I suggest no. If anything harms ants, it likely harms others as well. Besides, unless it reaches problematic levels, they are just part of the cycle.
Shiny leaves – often mean honeydew. The honeydew should be washed off, otherwise it attracts moulds that can kill your plants. As you wash it off, check under the leaf above and you will find a phloem-feeding insect (produce honeydew from plant sap) like aphids or whitefly. (Some phloem feeders, like spider mite, do not produce honeydew).
Curled leaves – open any curled leaf and look inside. It might be aphids – it might be a totally different surprise.
When you’re in the garden, think of yourself as a facilitator of life. You are growing plants, and habitats. Supply a water feature to add biodiversity. Compost regularly to facilitate life in the soil. Do not attempt to control life, or rid the garden of any one thing. Remember, everything has its place. For example – the perpetually hated yellow-jacket – seen here devouring a caterpillar that was eating my radishes. Thank you – but I will struggle to call you “beneficial.”