Some green beans climbing the federation fencing wire. Lush, happy and producing loads of beans.
Let's have a closer look though....
Does the sight of this cause you to gasp and quickly head for the pesticide?
It certainly does for most people. Even organic growers reach for pyrethrum (because it's safe and natural right?) or some other concoction of rhubarb leaves or tobacco.
WAIT, can I ask you to spend 10 minutes before you do and really look at the plant and ask yourself a couple of questions first.
There is some leaf damage but there are also more flowers and plenty of beans. The vines seem to be in good health. Healthy plants should tolerate a reasonable amount of attack from pests.
Don't reach for poison just yet.
There are a couple of dead cabbage moths (bottom left) within but I think they have sought shelter here. I bet they have laid their eggs elsewhere. I can't see their eggs hanging from the underside of the leaves or their chubby bright green caterpillars munching away.
I've searched and searched but can't give you a definitive identification of this common garden moth we get here in Tasmania. It is sheltering from the mizzling rain. The moth itself is not a problem but the larvae that hatch are leaf eaters. During my quick inspection I only see two so they are clearly not in outrageous numbers yet.
Here is a green shield bug. Shield bugs make up a large common category and are sap suckers. In great numbers these could definitely ruin your plant. They are easy to spot because they don't particularly hide from predators. They do tend to be a colour that blends with their surroundings but they also have stink glands that secret a foul smelling liquid, hence their other common name of stink bugs. Because of their harder shell, pyrethrum is usually not effective anyway. So hold that spray!
Ahh, the nymph stage (young before adult stage) of the above green shield bug. I am no entomologist but I suspect the colourings are for warning or "foxing" as it probably hasn't developed it's stink glands yet.
This is significant though. I can see six nymph shield bugs in a small space. Numbers are multiplying and definitely could do significant damage but experience has shown me that the plant will take a bit of sap sucking.
Some baby spiders show me that other predators are in the area.
Consider first and remember that spraying a control substance will also kill the predators that are helping you with your problem. Within this vine is probably small frogs and stick insects who also rely on bugs for food.
So standing back and weighing it all up....
The plant has been producing well and I have been picking beans for about six weeks. yes there are some holes and webbing leaf damage but the beans are tender and juicy. Reasonably I can expect another few weeks of picking and I weigh that up with wading in and killing the bugs. What would I gain? Another week or two of cropping? By then the beans are getting tired any way.
The shield bugs perhaps look like they are increasing but natural predation could take care of that within the next week. Given that pyrethrum isn't effective there is no point spraying. My preferred method of control is manual in most cases anyway. In this instance you would use a small brush to move them into a jar or a pair of forceps because remember, they secrete smelly stuff and you don't want that on your hands.
From my experience in the garden, I find the key is to keep things in balance and everything will cycle and take care of itself.
You definitely DO NOT want to eradicate any one thing.
Just because it is a pest doesn't mean that it doesn't have a vital part to play. Everything is reliant on something else. It's all part of the cycle or the chain. Think of yourself as the custodian of the garden rather than the controller. Your job is to aid and assist not to seek and destroy.
I haven't used any sprays in my garden, organic or otherwise in at least 20 years.
Spend a little time and weigh it all up, including the consequences of wiping out not one but several species. Could you be in fact doing even more harm than a few chewed leaves?