Phil Stevens

Kia ora Debbie -

The reason DOC got involved was because the large white apparently has a taste for some of our native brassicas, while the small white mostly goes for cultivated plants. If it were just another pest of arable or horticultural crops, the task would have been the job of the Ministry for Primary Industries. The fortunate bit was that the butterflies were noticed early, before they had a chance to really start breeding and spreading beyond the small area that they had colonised, and that was a big part of the the operation's success.

I'm with William on the suggestion to increase your predator habitat and try to bring in reinforcements to help control the butterflies. I grew stuff in Tucson for many years and my best assistants were things like lacewings, ladybugs, thrashers, and lizards.

Um, don't want to rain on anyone's campfire, but we have not eradicated the white cabbage butterfly here. They are an extreme pest, to the point where I've given up trying to grow brassicas for 4-6 months out of the year. My horseradish always gets skeleton leaves. Any stray mustard plants out in the paddocks are destroyed. Seedlings sown in autumn for winter and the following spring have to be netted and watched daily.

The article is referring to a second species, the "large" white cabbage butterfly, that was successfully contained around Nelson and is now probably gone. But the small ones are everywhere, thanks to the common planting of fodder brassicas and turnips as animal feed crops. If the farmers in each district would agree not to plant any about one in five years, we could get a handle on it using a combo of neem, Bt, and the UV tricks. But they won't have a bar of it.

That's wild. I would not have expected such big and healthy-looking animals to expire from falling into a hole like that. Are you able to do a postmortem or get them to a vet for an autopsy? I think something else might have been at play....

Mike, I think these eggs get laid on the cap. At least that's the case if they're the eggs of flies or flying beetles, which are the most common ones I see referred to as pests of edible fungi. There is also the Sciarid genus of flies, commonly called fungus gnats, who lay eggs on the ground and their larvae burrow in search of mycelium.

Hey Boris - I feel your pain. Our wine caps (and oysters, and pretty much any soft-fleshed fungal bodies) get pretty infested with maggots. It seems to be worse in warm weather, and I have noticed that the initial flush in a given spot is more likely to be free of them than subsequent ones. The adult flies may not be very strong fliers.

My main strategy is to do daily checks of the places where I think they're going to pop up and try to pick them on the early side, before they get riddled. I wonder if it's worth trying to put a fine mesh over them when they first emerge to give them an extra day to grow before picking...this will be the next experiment. I don't know what preys on, traps, or discourages the adults from coming and laying their eggs, but if there are biological controls that would be nice.

And indeed, hardwood biochars have higher mineral content than pine, including the species you mention. Now, if you want a more pozzolanic char, use straw, chaff, rice husks, or bamboo, as these will all have much higher silica content than wood.

Again, I cite from direct experience but there is a large body of research out there if you want to go looking for it.

Richard, my claim about biochar acting as a pozzolan is derived from direct experience and I presume it is a result of the ash fraction in the char, and may also result from the high number of functional attachment points on the surfaces of the particles, which would (in theory at least) enhance the carbonation by providing nucleation sites. There is also the increased aeration from the porous structure.

Using higher ash content hardwood chars gave me a harder final product than a test batch of pine biochar.

Sunchokes are handy because you harvest them in the winter. Just dig what you need to feed each day (or week). Lots of nutrition and they enjoy having something to peck at.

Good one Heather. Hadn't twigged to that!

I suspect the combo of sheep manure and fert might have been a little much. RO water from your house system is great. Cristo's suggestion of capturing the runoff from the drenching is a good one, as is checking for dry pockets in the root zone.