My organic garden was ravaged by pests this year, but my cabbages took a special hit. In the meantime, I was wondering if I can harvest the tender leaves anyway and try again to protect them next year. I don't see any insects on them, but I wonder if it is proper to eat them and whether they will taste bug-flavored. Thanks.
All of the cabbage leaves are edible, and they won't taste like bugs. Leaves with holes might not be appealing to dinner guests, but no harm or bad taste will come to you and your family eating them. Just give them a good rinse before you prepare to make sure any insects or insect remnants are washed off. I'm not sure what organism ate your plants but check along the stem and underneath the leaves as this is where caterpillars and other pests hide. If you plan on preparing these leaves by cooking or making coleslaw just chop into small pieces and you won't even noticed the holes.
Kudos for going the organic route. It can be challenging with cole crops to keep the pests under control. I've struggled with cabbage worms the last two years, so next season I'm going to invest in floating row covers. I tried a variety of organic/natural sprays but I think entirely covering cole crops is the way to go.
I would not eat them, just because there is very little left.
I would have no problem eating leaves with little damage. These are just eaten (by expert), so they are good, and they don't leave traces (and poo), no more than usual insects which are not eating the leaves. In any case you will clean them with water, and then cook them.
So there is really no problem for small damages (like the leaf on the top of the image). But for the leaf on the left, you have a few green parts and mostly veins.
It looks like you have cabbage worms. This is a common problem with brassicas and the symptoms are clear. You should check under the leaves and you will most likely see green worms camouflaged with the leaves. Sometimes they are hard to spot but based on the damage I suspect the works are a good inch in length. Not much you can do not but to prevent further damage, go and pick out the worms and the damage will stop. Next year, take action earlier to reduce the damage and as suggested by someone else, use a row cover.
I generally eat the leaves so no harm. Just inspect them carefully and wash them to get rid of the worms or other remnants.
Floating row cloth is absolutely necessary to have around as there are many uses for this stuff. But the Brassica family of cabbage, kale, broccoli etc. Really need to be covered as soon as they've been planted primarily for the cabbage fly whose larva eat the roots. That wasn't what ate your leaves. Possibly flea beetle.
Those leaves are important so your plants can make enough energy with which to grow the cabbage. That little guy in the center needs to be fed and that is only from photosynthesis. You are doing what the insects are doing if you eat the leaves. Cutting out the photosynthesis necessary to make the energy to grow the cabbage as well as stressing your plant and making it more vulnerable to insects.
Vegetable gardening is important to do as a way to get more successful each year. You need to learn what insects are causing damage to understand their life cycle and be ready for them next year. There are small windows of time where certain insects lay their eggs, or like flea beetles eat your mustards and cole crops leaves. Knowing your 'enemy' is half the battle, grins.
I use row cloth as soon as I've planted my cole starts. That stays there for a month and one half and I take it off because that is the period cabbage fly are laying their eggs at the base of your cabbage or broccoli. The row cloth edges are buried with soil so the cabbage fly and the cabbage moth are unable to crawl under to lay their eggs in the soil around the roots.
I also use a 'trap' crop for flea beetles. This is a mixed crop of mustards and cole/brassica in one 6X6' bed. This is usually my 'salad bowl' bed of the season. I combine all kinds of lettuce seed, radish, mustards, kale, carrots...into a large hole spice shaker and sprinkle the entire top of this bed. I have salad material all season long, when I harvest the radishes which are first to mature that leaves more room for other plants. I don't worry about cutting the lettuce tops I pull the lettuce roots and all to thin the bed.
Meanwhile, there is a time in early spring when flea beetles go nuts for about a month. They go nuts on the mustard and kale only. I'll have broccoli and cabbage and cauliflower and kale elsewhere in the garden and the flea beetles are not interested at all...in my 'cash crop'. This 'Trap crop' gives insects something to eat and they really do leave your 'cash crop' alone.
You need to pull up a cabbage and check out the roots. Very likely you've got Cabbage Fly damage of the roots. I've gone all season growing cabbage only to find a beautiful healthy looking plant just falls over and dies because the roots were eaten and/or the main stem was eaten through. Aphids will be another problem late in the season.
You could also have cutworms. Do you know if you've got slugs? Go out at night with a flashlight and do a few inspections. I can see powdery mildew has begun on that top full leaf. You'll need to start spraying a 1:9 solution of milk and water, top and bottom of leaves. That has been working for me. I'd also cut off all the leaves that have been skeletonized. They are no longer able to make food for the plant by photosynthesis and the material is stopping the flow of air. Good ventilation and moving air is antithesis to powdery mildew.
Is this garden out of doors? All those dead leaves and mulch on your soil is also a great place for insects to hang out while they decimate your garden. You are sort of providing a super bed and breakfast!
One more thing; are you fertilizing? Organic gardening is loose label. All gardens are artificial and we humans have to add chemistry necessary for photosynthesis or plants will just not be able to make their own food. Fertilizer is not food. Compost is not food. Healthy, thriving plants are able to deal with a little insect damage. Too much fertilizer can have the same effect by making plants even more susceptible to insects or just a little too much fertilizer can kill your plants before worrying about insects.
I'd like to see one of your cabbages' roots. When you get a chance to pull one up please take a picture to send us. Take a good look in the soil around the base of your plants. Only takes one cutworm to do a lot of damage. There is more than just one insect doing this damage, normal.
And, pesticides are never necessary and totally verboten on edibles. If someone uses a pesticide (herbicide, miticide, fungicide are included in the word pesticide) it is because of a mistake we made and we are trying to put a band aid on the problem. Gardens are never to be considered 'natural' and 'organic' holds little definition.
Cut off the obvious foliage that has more holes than leaf left. Let us know what you've used for fertilizer if any. Include type of compost if any. If you eat those leaves you will taking away the photosynthesizing factories necessary to make a real cabbage.
Cabbage white caterpillars the top right hand side of the photo gave it away with the white fibres being left behind, you should not only easily find them- quite big but they poo little green droppings at the bases of the leaves. pick them off- no need for any fancy chemicals- way too expensive and poisoning one self is not a good idea when coming to vege. just net them or you won't get them! small mesh size and place the plants well away from the netting- in hopes the butterfly can't reach in and lay their eggs- the net should be at least 6 inches away from the furthest leaf trying to touch it- I did a net cage for a client this year and it took me about two hours to make one up 2 meters square and 1 meter high on a wooden frame made from old fence lattices- so not an expensive option. oh and they are edible but not really worth it at this stage better chuck them and start again. If the netting is about half a centimetre or smaller mesh and pulled tight- (allowed to hold a cup of tea on it)then light issues are not a problem- only one layer of netting is fine enough- should do the trick. idea is not to trap anything within the net like half dead birds- not very nice to find next morning.