Reaction to pyrethrum

[Tree]

Hi

A couple of days ago I sprayed a number of plants with a pyrethrum insect spray (pump) and many now have burns on their leaves. :confused: The plants mainly effected are catha edulis and argyreia nervosa. The plants look like they have a shiny waxy coat on them with light patches and spots on most leaves.

Has anyone had a similar experience?

Thanks

[mescalito]

It maybe sunburn from the water left on the leaves??

Other than that,I've had no probs!

[Stonehenge]

Many plants are sensitive to insecticide and fungicide sprays. It might be the carrier rather than the pyrethrum itself. Always test a small branch or a plant you don't mind losing before doing any large scale spraying with a new compound. Even with a spray you've used successfully in the past, it's best to be careful when using it on any new plant. What doesn't phase one plant will kill a sensitive one.

BTW, tell me about your khat plants. Have you eaten them yet? What was it like? I'd also be interested in garden tips. I'm growing some myself.

Stoney

[planthelper]

apart from leave miners, catha edulis has got only a few pest problems.

i am growing qat since 13 years and never had to spray them.

so i ask you why did you spray them at all?

you described the injury well,

the story's moral: don't use pyrethrum on catha or

if you have to, wash it of with water after seconds.

and please don't use sprays during bright sunlight hours! ever heared of phototoxic symtoms?

[Tree]

Thanks for your replies

I think that you are right about the sunburn and phototoxic symptoms.

The reason I sprayed them was to eliminate a white fly infestation as the plants were being moved into a new glasshouse. Basically all plants that came from the infested area got sprayed. The thing is that I only sprayed a fraction of the plants incase there was a problem, but only left them a day before deciding to do the rest. It took two days for the problem to appear.

quote:

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"the story's moral: don't use pyrethrum on catha or if you have to, wash it of with water after seconds.

 

---

True, One lesson I wont be forgetting soon.

Luckily it was not all of them - all the plants that are outside are bug free.

Do you think they will survive this abuse?

Will these plants be sensitive to the sun for a while, if so should I keep them out of it? Should I try and wash them?

Thanks again, takecare.

[Guest d0tb0y]

Anyone know if salvia divinorum is sensetive to pyrethrum?

I've sprayed the entire plant during the past week or so, using confidor and yates scale gun.

Scale gun: petroleum oil, pyrethrins, piperonyl butoxide

Confidor: Imidacloprid

Dunno if this is even the cause, but after spray with these both, i've noticed moderate (but not fully grown leaves) falling off upon touch. the leaf and stem fall clean off the main stem of the plant, without a trace of internal rotting at the point of breakage, or anything. just as if you cleanly snapped it off with your own hand.

edit: would a systemic fungicide be more appropriate to tackle this probably 'internal' problem rather than spraying surface-treating materials?

[ 24. July 2003, 18:35: Message edited by: d0tb0y ]

[Torsten]

see my response in other thread.

pyrethrum is safe, however some of the other stuff may not be.

[Stonehenge]

I would recommend an insecticidal soap such as Safer's. I've never seen it harm a plant. It will kill the insect on contact and does not leave a toxic residue. You can wash the item and eat it the next day. I don't know if you have safer's in Australia but there must be something equivilent.

Stoney

[Torsten]

stonehenge - I presume such a soap is a combo of soap and an insecticide, eg pyrethrum??

Sounds good although I have never used them.

[Stonehenge]

Torsten

No, an insecticidal soap is not a soap plus an insecticide. It's just a soap which kills by a more or less mechanical action. It causes the outer layers of the insect's body to dry out by dissolving the protective coating. This makes the insect loose moisture and die quickly. Safer's is a potassium soap that's been around a long time. If you can't find something like it, you could try ordinary liquid dish soap. With the safer's I use 1/2 tbs with 12 oz water. I don't know if the dish soap will work as well or the exact amount to use but you could try it. I've heard dish soap does work. As with all new things it's best to try it on a leaf and make sure there is no reaction before doing large scale work. This type of insect killer does not have a residual effect. You must spray the insects directly to have any killing action. It also does not kill the eggs. Horticultural oil will work on eggs as well as other stages and adults. Neither of these are poisonous.

Stoney

[Torsten]

thanks for clarifying that!!

I presume the potassium soap is preferable to prevent sodium toxicity in the plants.

[mescalito]

I dunno about you guy's, but the white flies around here seem to love to stick to the underside of the nicotiana ,might make a good companion plant?

[Stonehenge]

Potassium is better for plants than sodium. Safer's is just made for plants and works very well. I've never seen it burn a plant.

Mescalito, I'm not sure I understand how they "stick" to the undersides. Whitefly will feed and lay eggs on the undersides of leaves. Do you mean the flies are dead? Nicotiene kills many insects but I thought whitefly were able to attack tobacco plants. I would spray with safer's and with some bt if you want to be sure to get rid of them.

Stoney