Pre-emptive approach to Boisduval scale

[ArronOB]

I have about 40 small cattleya hybrid plants growing on our windowsills in 3 or 4 inch pots (bark and charcoal with a few threads of sphagnum). They are in perfect health. In a couple of weeks we move to our new home, and they will be put outside where they will stay permanently, under some shelter. Average winter temperatures will be a bit low for outside growing, but they will get by. I'll set up an automatic watering system - daily in summer and weekly in winter.

Now I've grown cattleya hybrids in the past and I've learnt that in our environment the only real insect/arthropod pest is boisduval scale, but its very pervasive and very difficult to control. Id like to give them some type of pretreatment before putting them out.

I should point out that I'm not interested in solutions that involve rubbing the plants with alcohol or oil or soap or cotton buds or whatever. Past experience tells me that if I let the infestation start, itll be a loosing battle from then on.

I also find that with small plants like these I (clumsy) do too much damage handling them excessively.

A bit of Googling found a grower in Melbourne who claims to prevent scale completely by alternate spraying with Confidor and Diazanon. I wouldn't mind using the Confidor but I would be reluctant to use something as toxic as Diazanon.

If nothing else arises, I'll probably just give them 3 weekly treatments with Confidor before putting them out then hope for the best. At least its systemic, but I suspect there are better approaches as I've been told the scale will simply develop resistance to this product over time.

Any other suggestions ??

cheers
Arron

[ryrycochinco]

I've heard adding one part hydrogen peroxide to ten parts water is a gentle way to keep foliage pest free. I'm not sure if that would work as a one time precautionary treatment, but I'm sure spraying them down once in awhile or adding the mixture into your watering system would be beneficial. I think using harsh pesticides from the get go is a little excessive and won't have the necessary longevity to work well as a one time treatment. Anything you do will have to be done routinely, so it might as well be gentle.

[Roberta]

Confifidor is Imidacloprid (same stuff as we have in Bayer's Advanced) It's a good systemic. However, I suggest that you not use it as a prophylactic - I have found that the Catts that develop scale tend to be the less healthy ones - so if they're healthy, they very likely won't get infested. And to use a pesticide ahead of need (or repeatedly) is asking for development of resistance. Watch and pounce on it if you see it, but use it (and anything else) surgically. If you do have to treat, alternating different products is vital to avoid the resistance issue, and also treating several times - once only gets the adults so you have to go after the subsequent generations to knock down an infestation and keep it down.

[ArronOB]

Originally Posted by Roberta

Confifidor is Imidacloprid (same stuff as we have in Bayer's Advanced) It's a good systemic. However, I suggest that you not use it as a prophylactic - I have found that the Catts that develop scale tend to be the less healthy ones - so if they're healthy, they very likely won't get infested. And to use a pesticide ahead of need (or repeatedly) is asking for development of resistance. Watch and pounce on it if you see it, but use it (and anything else) surgically. If you do have to treat, alternating different products is vital to avoid the resistance issue, and also treating several times - once only gets the adults so you have to go after the subsequent generations to knock down an infestation and keep it down.

Thanks Roberta, that sounds like excellent advice. I’ll put them out and keep a close eye on them. Hopefully I’ll never need to spray, the new microclimate is significantly more benevolent then the old.

There is one complication though. I also have some old, mature plants growing outside - mainly coolgrowing laelias like anceps. Some of them have scale. Not bad infestations. I occasionally attend to the scale but generally they don’t really seem to get much better or worse. If I spray them with a systemic, will that lead to any complications. I’m thinking about resistant bugs making their way to my cattleya hybrids then being impossible to get rid of?

[Roberta]

If they have scale, spray with systemic And spray again in a week, and a week after that (preferably with a different class of pesticide) . (If you can get Diazanon, use it as your "alternate pesticide") The absorption of the systemic pesticides into the plant is very slow - orchids grow really slowly... you want to knock it down right away. In general.. if you have an infestation, treat it on the affected plants, and do it thoroughly (repeatedly to get the progeny - that will also tend to avoid resistance, you want to kill it not stun it). If you get it out of your vigorous plants that seem to put up with it, it won't be there to infest the more vulnerable ones. Just don't do it prophylactically .

Another reason for being surgical about pesticide use... you then greatly reduce the chance of harming good insects such as bees, by minimizing the amount that you put into the environment.

[ArronOB]

Ok, thanks Roberta.

Arron

[dounoharm]

I think a lot of the fright of using insecticides comes from using them in an 'open' environment where it could drift to areas where it is not wanted. I do use chemicals on my orchids IN THE GREENHOUSE, but, I do not use them outside, as danger to 'good insects' is too great.

I really don't know your climate, but I would hesitate spraying systemics outside.....I grow organic veggies, so I have to be really careful in everything I spray....outside, I figure on the old adage, plant by 3...one for the gods, one for the bugs, and one for me...lol

I use dawn dishsoap, gallons of it I think, all summer...another favorite is that peppermint oil soap, dr bonner's.....very rarely will I use sevin, only when I see an infestation....I use it mixed with the soap as a liquid spray.....better yet is diatomaceous earth, which can be dusted or sprayed....

with your orchids, since you don't have so many, you can put them in large leaf bags and spray the systemics...its a little trouble, but sometimes you must!...always dry them in shade before returning them outside....

scale is one of the nastiest bugs...they retreat, and form new battle lines!...its a WAR! I suggest that you handle the scale outside before you put little cats out there...

I like to keep mine indoors for those reasons....I run a tight ship (greenhouse) with no tolerance for bugs! good luck!

[bil]

I simply won't tolerate scale. In your shoes I would hit those outside plants, and everything near them with Imacloporid. Repeat in 2 weeks, and if they persist, another treatment two weeks after that. If you are really worried that they are developing resistace, then dose with Chas 48 inbetween each Confidor treatment. Anything that survives that is a genuine problem. DO make sure that you treat all the surrounding plants, and check them for scale. Expand your treatment to cover all possibly infested plants. Scale will hide away on almost everything hat grows. OK, you might kill a few bees, but better that than be perpetually infested with scale.

[ArronOB]

Dounoharm, I like your idea of using a leaf bag to control spray drift. I think I might make something up using an upside down plastic garbage bin. Sort of a mini spray booth. Not only would it limit the impact of the spray on the environment but I think it would make for better coverage and use less product.

Cheers
Arron

[Orchid Whisperer]

You can minimize drift by only applying on low to no wind days. Also, take plants to a surface like a driveway or deck where any drift will not land on plants.

The Confidor main ingredient (Imidacloprid) is pretty low toxicity except for insects. It is used at concentrations hundreds of times stronger as a flea control on dogs (in USA Bayer "Advantage" or "Advantix" products).

To avoid building a tolerance to insecticides in your insect population, I suggest only using when you see insects. Also, rotate periodically with another systemic (see if you have the pesticide Acephate in your country, or another systemic that works on orchids).