Pest control

[Eric Williams]

Hi all, I only have about one hundred and fifty plants to look after. Being retired I can check for the usual c and s pests and treat accordingly. I wonder what the cactus growers in Holland for example do as they have many thousands of plants to care for. Do they spray to prevent any problems when no problems exist ? Thanks

[Paul D]

Hi all, I only have about one hundred and fifty plants to look after. Being retired I can check for the usual c and s pests and treat accordingly. I wonder what the cactus growers in Holland for example do as they have many thousands of plants to care for. Do they spray to prevent any problems when no problems exist ? Thanks

Hi Eric,
I've wondered about professional nursery practices for quite a few years too. I think the answer is... if you assume problems don't exist then you are in for a disappointment! Pre-emptive strikes seem to be the way to go. Waiting until pests become visible usually means they are well towards getting established. I keep hoping someone who is a professional nurseryperson will chip in but despite there being several on the membership they keep their cards close to their chests.
What I do, which has been fairly successful over the last 3 or 4 years, is spray at the end of April when temperatures warm up a bit; spray again with a different product about 5 days later; then spray again with a different product 5 days later. That breaks the cycle of e.g. mealy bugs. I then spray when the summer starts at the end of June, and again 5 days later with a different product, mainly to target thrips and spider mites.
Finally, I spray twice in mid to end of August to get rid of any build up before winter dormancy.
Whether that is right or not, I don't know, but (so far) it seems to work for this situation. It might be overkill.
I should add that I spent time (and money) getting my PA1 and PA6a tickets at the beginning of the year and so I'm now able to buy and use proper insecticides. The word on the course was that products available to the public are not worth the money.

[JonNo]

I read your post Paul with increasing optimism - until the final sentence... So as far as we ordinary folk are concerned nothing we spray with is going to be of any help then?

[Chris L]

I often wonder with the big dutch nurseries if:

---they are pretty much all going to use peat and only peat as their growing medium.
---they are growing plants that are constantly in growth.
---they likely have stronger chemicals
-------which (if the plants are growing all the time) and in an absorbant medium they cannot help but soak it up.

whereas, a lot of our "problem plants" invariably are slightly (or a lot) sickley and usually with damaged or missing roots and are maybe in a compost that doesn't get uniformly wet all the way through.

[Phil_SK]

Big nurseries probably don't keep 'rescuing' plants from neglected collections and reintroducing pests every few months.

[Cidermanrolls]

I read your post Paul with increasing optimism - until the final sentence... So as far as we ordinary folk are concerned nothing we spray with is going to be of any help then?

Not really. The amateur use products go through the same licensing process. Proof of efficacy at the recommended dose is part of the registration for professional and amateur products alike.
The big differences are the price and the range of actives.
Dose for dose, amateur use products cost many times more than the equivalent professional use product. And the amateur market is limited to a small range of products that have been shown to be OK in the hands of someone with no training in the safe use of hazardous chemicals and who would not be expected to have access to personal protective equipment.

[SimonT]

An issue with amateur products available today is that they are not very persistent. So for example, they might kill every adult pest on the plant on the day of spraying, but maybe some eggs survive. A week or two later those eggs hatch, by then the pesticide has broken down and so these new pests can grow again unchecked. This leads to an endless spraying cycle, the pests are never really eliminated and if you ever stop spraying the pest soon comes straight back in numbers. And OK limited chemical persistence might make a lot of sense to minimise environmental impact in general, but is this really the case for indoor non-edible plants? I'd rather spray once, eliminate the problem, and stop it coming back in by carefully treating any new plants I buy. The pests we suffer from are mostly not native- they only exist indoors and must be physically spread between isolated growing spaces.

[Stuart]

If its any consolation, it’s not too difficult to spot mealy bugs in some of the larger Dutch commercial nurseries.
Stuart

[habanerocat]

Well this is it. End of an era.
My last bottle of Malathion is empty.

I remember buying six bottles when it was being withdrawn from the market. It must be well over 20 years ago.
With its help I cleaned my collection. Greenhouse was full. No new arrivals. And for many years I never had to use it.
Illness and frost combined to decimate my collection. But since the new greenhouse and many new arrivals they (mealy bugs) are back again, worse than ever despite my best efforts of quarantine.

So is that Bug Clear Ultra any good?
Or what are ye using now?

[habanerocat]

It was strange over the years, despite the bottles being new and well sealed, the liquid volume inside the bottles almost halved.
Still worked though.....