cabbage

[songbird]

as our space is usually limited and i can't cook it anyways we've never actually grown cabbages before this year. the difference this year is someone we know who makes saurkraut and Ma wanting to do something nice for them. we put in 12 plants.

of the 12, 1 is decidedly different in leaf shape and i doubt it will be a cabbage at all. 1 other is much smaller than the others, but that is because it is shaded in the afternoon for a few hours. it is still green and growing fine.

the cabbage butterfly/worms are doing a lot of damage. today i went out to pick them off and then i sprayed the plants down to rinse off all the green poop they left behind. this way when i go out again to find more worms i'll be able to see if any new piles are showing up.

as i've not really cared much about the white butterflies before to pay attention to their life cycle i figured i could ask the experts here about them.

i'm assuming that as long as they are flying around they are capable of laying eggs. so the quest of picking worms off will likely be until i stop seeing them flying around.

as to specific questions, do they ever give up? or can they have more than one generation per season?

the cabbage is getting a more compact inner set of leaves now, do the worms keep burrowing in or will the plant be able to form a head anyways if i ignore them? it looks like it can be hard to get all the worms off of those inner leaves without breaking them off.

when the worms are done where do they hibernate/pupate?

i had a nice handful of them today and put them in soapy water to drown them. poor guys.

yes, i know i can google all of this, but it's fun to also be able to talk to people about their experiences.

as for control, hand picking seems to be the only option as i don't spray anything other than water on the plants. if there are other ways of controlling them (bugs to encourage other than praying mantis or birds that will eat them or the butterflies, etc.) i'll be interested in hearing your experiences with what you've attempted and what's worked the best.

thanks!

songbird

[Roy]

Derris dust will control those cabbage moths...why don't you use it?

==

[Billy]

Toxicity

Rotenone is classified by the World Health Organization as moderately hazardous.[14] It is mildly toxic to humans and other mammals, but extremely toxic to insects and aquatic life, including fish. This higher toxicity in fish and insects is because the lipophilic rotenone is easily taken up through the gills or trachea, but not as easily through the skin or the gastrointestinal tract. Rotenone is toxic to erythrocytes in vitro. [15]

The lowest lethal dose for a child is 143 mg/kg. Human deaths from rotenone poisoning are rare because its irritating action causes vomiting.[16] Deliberate ingestion of rotenone can be fatal.[17]

The compound decomposes when exposed to sunlight and usually has a lifetime of six days in the environment.[18] In water, rotenone may last six months.[citation needed] Parkinson's disease

In 2000, injecting rotenone into rats was reported to cause the development of symptoms similar to those of Parkinson's disease (PD). Rotenone was continuously applied over a period of five weeks, mixed with DMSO and PEG to enhance tissue penetration, and injected into the jugular vein.[19] The study does not directly suggest rotenone exposure is responsible for PD in humans, but is consistent with the belief that chronic exposure to environmental toxins increases the likelihood of the disease.[20]

In addition, studies with primary cultures of rat neurons and microglia have shown low doses of rotenone (below 10 nM) induce oxidative damage and death of dopaminergic neurons,[21] and it is these neurons in the substantia nigra that die in Parkinson's disease. Another study has also described toxic action of rotenone at low concentrations (5 nM) in dopaminergic neurons from acute rat brain slices.[22] This toxicity was exacerbated by an additional cell stressor - elevated intracellular calcium concentration - adding support to the 'multiple hit hypothesis' of dopaminergic neuron death.

The neurotoxin MPTP had been known earlier to cause PD-like symptoms (in humans and other primates, though not in rats) by interfering with Complex I in the electron transport chain and killing dopaminergic neurons in the substantia nigra. However, further studies involving MPTP have failed to show development of Lewy bodies, a key component to PD pathology. Therefore, the mechanism behind MPTP as it relates to Parkinson's disease is not fully understood.[23] Because of these developments, rotenone was investigated as a possible Parkinson-causing agent. Both MPTP and rotenone are lipophilic and can cross the bloodbrain barrier.

In 2010, a study was published detailing the progression of Parkinson's-like symptoms in mice following chronic intragastric ingestion of low doses of rotenone. The concentrations in the central nervous system were below detectable limits, yet still induced PD pathology.[24]

In 2011, a US National Institutes of Health study showed a link between rotenone use and Parkinson's disease in farm workers.[25]

[Roy]

So thoroughly WASH the dust from the cabbage and there should be NO problem.

Sheesh, you people think that everyone wants to ingest poisons. Derris dust breaks down naturally after exposure to air. We always WASHED our cabbage before usage...what is preventing you from doing the same thing?

[phorbin]

BTK in most cases does just fine.

Why don't you try it.

[Roy]

I definitely will try it...now that I have some information on it and where it is available. Thanks for the tip.

[songbird]

Roy wrote: ...

doesn't meet my requirements.

Bt doesn't either.

songbird

[songbird]

phorbin wrote: ...

doesn't meet my requirements.

songbird

[songbird]

Roy wrote: ...

some of us find the "poison" approach unethical or damaging in other ways (including intellectually).

some of us would rather explore other methods of problem solving gardening issues than applying a spray.

perhaps you've suffered from a derris dust exposure and it has damaged your brain? how could i trust your judgement?

songbird

[Ian Gay]

Since there's only 12 plants involved, it's not much work to just pick the caterpillars by hand and stomp on them.

[songbird]

Ian Gay wrote: ...

yep, that's what i'll be doing for now, but still reading and interested in comments about life-cycle or habits of creatures and plants.

so far one source says to enclose the head in stockings to keep them out, but that doesn't take care of those already inside or tell me if the plant will out grow those inside (as they must eventually eat enough at some point...) and end up with a solid cabbage head after all.

looks like only one life-cycle per season.

the other thing is that there are very few decoy varieties around. i have almost no other brassicas in the gardens/yard. so these plants are acting like a magnet...

songbird

[David Hare-Scott]

Yes

No they never give up except when it is too cold, yes they can have many generations per season depending on how long your warm season is.

The worms will only attack the outside but still will cause quite a bit of waste.

Where you can't find them.

By far the simplest solution if you don't want to spray is netting. Use polymer netting that is used on fruit trees, the mesh is about 2cm (1in) and the butterflies cannot get through. No butterlfies means no eggs, no eggs no grubs. Youy can make hoops out of polypipe to stand the net off the cabbage. The same applies to any brassica that the cabbage butterfly eats.

David

[David Hare-Scott]

Why?

D

[phorbin]

My response was to Roy's suggestion.

Having read another post of yours, I'd bet that your biggest helper will probably be wasps.

If you've watched them patrol cabbages, broccoli and the like, you'll have noticed that they are very thorough and go over every leaf top and bottom until they find something.

We let the wasps nest mostly wherever and have their own harvest. Between our picking and squashing and their stinging and carrying away, the cabbages do well.

One season we had a huge paper wasp nest in the garden shed and no cabbage caterpillars.

It's a bit different after the cabbages head up. Then our problem is mostly earwigs and slugs.

[songbird]

ok.

we have plenty of hornets/wasps around. they like the rocks in the rock piles, the backsides of stepping stones, many of the wind chimes or other decorations. also they often are nesting on the eves of the house (but i knock those down).

when we had scarecrows the wasps/hornets really liked those.

i've not ever seen them crawling on the cabbage plants, but will hope to see them soon. i picked about 70 cabbage worms today. will check them again in the morning. rinsing off the droppings helps find new ones.

will have to inspect more closely for eggs this morning.

as i've never grown cabbage before i'm guessing that is what is starting to happen now as the middle of the heads are starting to have more curling leaves packed together. the cabbage worms are doing a good job of chewing their way through those leaves.

luckily i don't think either of those are a significant problem around here.

songbird

[songbird]

dislike poisons in general. don't trust that this one only affects the bug in question. don't like repeated applications as that is expensive and also can breed resistance.

if there is resistance i'd have to continue to monitor and hand pick along with the repeated spraying -- just doesn't seem to gain much in the end. i don't mind hand-picking, just that i ignored them for a while (we had regulr rains for the past six weeks) as they were growing well and i had other things to do. when watering yesterday i noticed they were being chewed on...

now that i know i have to include it in the daily routine we'll see how it goes.

songbird

[songbird]

...

i may take a butterfly net with me as sometimes i can get fairly close enough to the butterflies.

i'm not seeing any reference which says that they will cocoon and hatch out again more than once a season. i do see references which say that they lay eggs all season and are fairly cold hardy.

that's ok. we just want organic/non-sprayed cabbage. if they have to cut around damage during processing that is fairly normal anyways.

hehe. probably some of them, but if they don't crawl far before spinning there's not much place for them to go in this particular patch. if they will use the underside of rocks then i can likely find some of them (and the raccoons will find some of them too).

if i can protect the heads using old stockings that would be much more preferable (less material used and less fuss and bother overall). just not experienced enough with cabbage yet to know how they work/grow/habit, etc.

my mistake was ignoring the plants to begin with, they looked good from a distance and i didn't need to water them for quite some time. with the white butterflies floating around i should have kept a closer eye on them.

as they say, yet another growth experience... next batch will get a daily inspection now that i see what the worms can do.

thanks, :)

songbird

[phorbin]

The problem is their pupation on wild hosts.

You can get them in the garden, but the wild mustards in the district are a little harder to find.

[Drew Lawson]

Very dated experience has me doubtful that a cabbage worm could ever get full.

I think the only zero-input method is enclosing the plants early (row covers or such). Otherwise, picking or poison.

My experience is with broccoli, but I assume they behave about the same on cabbage.

[Billy]

Larvae of the cabbage butterfly are green and very hairy, with an almost velvet like appearance. Older larvae may be up to an inch long and often have one faint yellow-orange stripe down their backs and broken stripes along the sides. Compared to other caterpillars, cabbageworms move slowly and are sluggish but they feed voraciously on both the outer and inner leaves, often feeding along the midrib, at the base of the wrapper leaves, or boring into the heads of cabbage. After 2 to 3 weeks of feeding, larvae pupate attached by a few strands of silk to stems or other nearby objects; pupae are green with faint yellow lines down the back and sides; there is no spun cocoon. The adult cabbage butterfly is white with one to four black spots on the wings; they are often seen fluttering around the fields. The whitish, rocket-shaped eggs are laid singly on the undersides of leaves.

Natural enemies can assist significantly in the control of imported cabbageworms. Important parasites include the pupal parasite Pteromalus puparum; the larval parasites Apanteles glomeratus, Microplitis plutella, and several tachinid flies; and egg parasites in the Trichogramma genus. Viruses and bacterial diseases are also sometimes important control factors in the field.

TACHINID FLY

(many species)

DESCRIPTION

Tachinid flies are North America's largest and most important group of parasitic flies, with at least 1300 species in the U.S. Adult tachinid flies resemble small houseflies and may be covered in dark bristly hairs. Their bodies measure anywhere from 1/3" to 1/4". Adult tachinids are commonly found pollinating flowers and resting on leaves. The adults are important pollinators and the larvae consume incredible amounts of pests.

LIFE CYCLE

Tachinid flies are parasites. Some female tachinid flies lay their eggs on the bodies of host insects, after which the eggs hatch and the larvae tunnel inside and excavate the host's body. Other species deposit live larvae directly into the hosts. And still other tachinids lay eggs on plants in hopes that the eggs will be digested by a host insect (caterpillars in particular) and gain access that way.

PESTS THEY CONTROL

Tachinid fly larvae help rid your garden of:

Caterpillars of many kinds (including cabbage worms and Gypsy moth), Colorado potato beetles, corn ear worms, cucumber beetles, cutworms, earwigs, four lined plant bugs, Japanese beetles, Mexican bean beetles, sawfly larvae, squash bugs, tobacco budworms.

Larval tachinid flies begin to consume their hosts by eating non-essentia tissue first; as a result the host will continue to grow and feed normally--for a while. Only when this material is fully consumed, will the larvae turn to eating vital organs. After all, it's in the tachinid larvae's best interest to allow their host to live as long as possible so they can grow fat and sassy. The larvae then pupate into adults either inside or outside their prey's body.

HOW TO ATTRACT AND KEEP THEM

Preferring to feed on nectar from small flowers, tachinid flies are lured to habitats rich in flowering herbs, especially those in the dill family: cilantro, dill, fennel, parsley, and Queen Anne's lace are very attractive. They also enjoy nectar from members of the daisy family including: Aster, chamomile, feverfew, ox-eye daisy and Shasta daisy. Flowering buckwheat is said to be another good draw.