If the transition period is long enough, the traditional seedling is allowed to grow. Two years is enough.

Thank you Hong Yu, my question was rather about annual vegetables like tomatoes, peppers, aubergines, etc.

You need to trust your field to be sure it is under organic cultivation for about three seasons. thereafter, you raise seeds from your first or second harvest to ensure progressive seed purity and satisfy your legislation.

Thank you Mr. Lewu. My question is not how to fulfill the legislation. I am just wondering whether legislation is or not too strict in this sense. I mean, I'd like to know whether after 2-3 months time from planting of the conventional seedling until collection of the fruits (let's say, peppers), traces of pesticides or inorganic fertilizers might be found in fruits. 

Legislation is legislation, unfortunately we cannot escape them.The only way we can be sure is if you run chemical test on your harvest. However, you may obtain third generation seeds under organic cultivation and test for presence of the chemicals. That will take you a whole year if you can plant under controlled environment and considering your seed does not undergo dormancy prior to the next germination. Good luck with your work. I hope this helps :)

Dear Rafael,

I think the way to address your issue is to collect the field history regarding pesticides application and the persistence of the same in soils. The time lapse alone is insufficient. For instance contact herbicides formulation are often short-lived, they are degraded actively by soil micro-organisms following their application within a few days. But you ought to bear in mind that soil property also affect persistence cum degradation for instance addition of incinerators ashes to soil has been found to inactivate if not reduce the solubility of herbicides in soil due to their absorptive capacity. 

There are a lot of field studies evaluating the persistence of pesticides in soils, I am sure you will find plenty on the web, from there you can appreciate/evaluates the potential residual effect of pesticides in your project with regard to what is permissible by the authority.

Good luck

J P

Thank you Jean Pierre, that's very interesting and useful. The point is that I'm asking as a organic farmer rather than as a researcher (unfortunately, currently I'm not involved in research projects nor have access to approppriate research tools). I'm aware that my question is unaccurate, cause I'm not giving quantities of pesticides, soil traits, etc. But, I'll try to re-ask the question.

Let's start with an organic field, with no pesticides residues in soil. Now, I buy in the nursery some seedlings of peppers, grown conventionally, so presenting standard levels of pesticides and inorganic fertilizers in its rootball. When planted in the ground, some of this pesticides will difuse into the soil (I didn't take it into account before, thank you Jean Pierre), and some will enter into the plant and may appear into the fruit. My question: under the standards of pesticides application by nurseries to the plants they sell, from the seed to the seedling, is it possible that we found pesticides in the pepper fruit?   

Maybe there's no point to ask this question from a scientific point of view without any further description, but it is sound to me as a farmer.

Thank you all

It is a good question. My understanding is that to a large extent it depends on the chemical used. Most pesticides are classified as "systemic" ie taken up by the plant.eg Roundup; "contact" ie act on contact eg contact herbicides like Basta; or "residual" ie remain in the soil and prevent weed seeds from germinating etc eg herbicides like Sencorex. Obviously residual and systemic types are more likely to persist in the environment. How long for would depend on a multitude of factors.

A vegetable plant cant take up a systemic pesticide like Roundup without being killed itself, but it could take up a systemic insecticide or fungicide. In fact this is how some systemic insecticides work - the chemical is present in the plant phloem etc and is injested by aphids or other pests.

A lot of vegetable and other seeds have a coating with gaucho (imidacloprid) which you have probably heard of in connection with bees. For example http://www.affaire-gaucho-regent.com/pdf_abeilles/chauzat-faucon.pdf

It is a systemic pesticide (insecticide/fungicide) and stays in the plant protecting it while it grows.

If a conventional seedling had a systemic treatment as above and was then grown organically, the chemical would persist inside the plant for some time. Whether that is long enough until fruit formation is a question I cant answer!

As a point if interest most countries have a pesticide control service which tests fruits and vegetables in supermarkets at random and they generally produce an annual report. It would be worth doing some googling in your country if you are interest. They generally test a range of products including organic, and they sometimes report what chemical is found. If you then google the chemical mode of action that lets you know if its systemic, contact, likely to have been used as a seed treatment etc

A thorough search of this kind of data would answer you question!

Hope that's helpful

Best wishes

Dear All,

As Kim wrote it this is a question of a thorough analysis. I note we may ingest more residues by inhaling unfiltered air than the pesticide residues of seedlings like those...

Dear Rafael Sesmero, you have been doing well when re-asking the question! in fact, pesticide residues will not appear in the pepper fruits, because the time from planting prior to the first harvest is more than 47 days (in morrocan conditions Under greenhouse, so more in your conditions). The maximum duration of persistance of any actual commercial pesticide in the plant is 35 days, so the answer is obvious.

By the other hand, in case of very lasting residues persistance, quantities found in the seedling will be diluted within the whole plant (biomass ratio= seedling/mature plant).

Regarding the legistation, the auditor will check the nursery technics if they comply with rules, and also the contaminations risk of the field in case of growing close to a conventional farm. In general, nurseries don't use too much pesticides, and in most cases, fungicides are more used than the others.

Good luck

Khalid

Dear Kim Reilly, your research proposal is very interesting! Based in non-experimental approach, just  a computer and internet, what makes it even easier to perform, and could be very informative. Thank you!

In order to make myself clearer with respect to my question, I recall a paragraph from you:

'If a conventional seedling had a systemic treatment as above and was then grown organically, the chemical would persist inside the plant for some time. Whether that is long enough until fruit formation is a question I cant answer!'

That is exactly what my question is about, whether we can say with a reasonable margin that a chemical will not be present in the fruit, starting from conventionally grown seedling and grown organically thereafter.

As a summary of your replies, I understand that this issue depends mainly on the nature of the pesticide (systemic/contact/residual), and specially its persistence in the plant.

Dear Khalid Azim, I understand by your reply that every systemic pesticide has a maximun of 35 days of persistence in the plant, and so, if the time lapse from planting the seedling to fruit harvest is longer, there'd be no fear of fruit contamination. That's a very pragmatic answer, because knowing the persistence of every pesticide used and the time lapse from planting to harvesting for a certain crop, we could make sure that no pesticide is in the fruit.

Some other questions come to my mind as a result of your reply: Do you know whether persistence times of pesticides are different for different families of plants? I mean, does eg. cucurbitaceae have the same ability to degrade pesticides as eg. solanaceae?

Thank you all

Dear Rafael, maybe my answer was taken in a Cartesian way. In fact, there are pesticides that remain up to 90 days in the plants (especially nematicides). But knowing that those nematicides are applied before plant establishment prior to plantation, the residues will not obviously appear in the fruit. So, persistence of any pesticides in the plant is linked directly to its period before harvesting (generally indicated in the pesticide box and notice).

Concerning the second question, I'm afraid there are few or no scientific data about how botanical families metabolite pesticides into pesticide residues. It still open but is very difficult because of two reasons:

1-Difference of metabolism is seen between two crop approaches with the same variety, than it's more difficult between two families. Accurate data are very hard to comment.

2-Pesticides residues are measured by HPLC (special columns) of GC-MS (if already characterized). One pesticide split into several molecules and then become hard to detect and expensive to set. In addition to that, notion of residues juice will appear to enter into a specialty between phytopharmacy and human health science. How a multitude of pesticide residues and in witch limit will affect humain health and antagonistic species on and around the crop?

I hope that I didn't diverge from the initial scope of the question

Best regards

Khalid AZIM