RE roundup around palms

[sonoranfans]

Having read Palmarati Keiths roundup articles:

http://www.palmtalk.org/forum/index.php?showtopic=29357

I started thinking about them. They make a lot of sense with strong empirical scientific underpinnings unlike so much of todays hot science topics. THere can be no doubt that strong chelate binding can make micronutrients unavailable to plants. But how will this effect palms and how long with the effects last. And can they be overcome by just over fertilizing with more micro nutrients? I inadvertently started an experiment this past february with two beccariophoenix alfredii. I had one established alfredii that had a mulch layer where little bermuda grass had penetrated, the palm had been frost burned badly last winter and came back strong. I pulled the grass out by hand and let the palm grow because at the time I had no roundup. I also had another one, bought at the same time (and size) where grass had invaded the mulched area. A week or two later(early march?) I applied roundup 2x over the course of the next 3 months to the second alfredii using a pump sprayer. I just tried to wet the bermuda grass foliage, in an attempt to keep the grass away from the root zone. In the mean time I fertilized copiously with lesco palm fertilizer(90 day release) and also florikan palm special(5-6 month release). I also used souther ag chelated(lignin)palm micronutrient mix and some spray and grow on these palms. So you could say I just plastered them with a mice balance of palm micros in instant liquid feed, foliar treatment(with cocowet to wet the filiar treatment of spray and gro), and a heavy dose of time release fertilizer(3-4 lbs per palm). The results so far are interesting. A properly fed alfredii is a nice medium green, not yellow. In my experience these palms do seem to take a little extra micros to get them to go green, not like wondowpane, more like phoenix rupicola. So today I went out and took pics of my two alfredii, both in 6+ hours of sun and high drainage sandy soil with plenty of water. Here is the one that didnt see roundup, its a nice green color even the new growth.

[sonoranfans]

And here is the one that saw roundup 2x this year, not getting the green color on the new growth, consistent with micronutrient deficiencies. The only thing that I can see I did different is the roundup treatment, as everything else(soil ammendment, sun,fertilizer, water) was the same. Now these alfredii are micronutrient dependent, most of my other palms are not so sensitive. But I would hypothesize that under some conditions, roundup use can cost you in the health of your palms. Maybe they dont get a yelloow color, maybe they just grow slower. Perhaps some that dont have micronutrient dependencies arent even effected. In my experience things are nto cut and dried in science, shades of grey is the most likely result. But to blow off some pretty sound empirical science is a risk you are taking with roundup use around root zones. I will post photos of these two again at the end of the growing season. For now, I am discontinuing roundup use around my more micronutrient needy palms and keeping up the over application of micros and ferts.

[Mike Evans]

Tom, what percentage of the leaves got burnt last winter? Looks like they are recovering well. I would not think that 2 applications on roundup would affect the palm that much, unless it rained recently after application. Are these the same ones I am thinking of?

[sonoranfans]

Tom, what percentage of the leaves got burnt last winter? Looks like they are recovering well. I would not think that 2 applications on roundup would affect the palm that much, unless it rained recently after application. Are these the same ones I am thinking of?

Yep mike they are the ones. The green one was about 90% burned by frost last winter(photos in the alfredii cold tolerance thread), the other one wasnt burned significantly, its in a warmer spot and was covered. The burnt one sure came back fast, Im happy with its recovery. I am excited about alfredii as viable palms here, but they do want their micros to look nice and green. I had some stubborn bermuda and weeds invading the one that got the roundup, the invading grass was substantial. I think the roundup gets into the soil through the plant roots, it just cant be avoided. the more plants, the more roots, the more roundup in the soil. I used one of those 1 gallon pump sprayers with the roundup, wet down the weeds, not the soil. I expect the "roundup" palm will recover this year as I keep the micros up. Only spears that have pushed and opened this year are effected. I also planted the yellow one a few months later last year so perhaps its roots arent as developed. It would seem that as palms develop more extensive root systems they are less effected at each level of roundup exposure. These alfredii and phoenix rupicolas are the only palms that I have trouble with keeping the green after roundup use. It doesnt seem to effect bizzies or sabals or even x-butiagrus. I havent used the roundup around archontos or several other species. It occurred to me that roundup might slow the growth in some species and not cause yellowing, depending ontheir micro needs/sensitivities. It also occurred to me that the soil type and watering rate would have an impact. I suspect slow continual watering in my sandy soil will rinse the glucophosphate out of soil more effectively than a fast, high volume watering. I base this hypothesis on solubility theory and chromatographic separations. We have had very little rain, perhaps that played a role as I would expect that consistent rain would rinse the glycophosphate from the sandy soil.

I have to say that the attachments that Keith offered in his thread(link above) represented some pretty sound research, though it was certainly focused on crops and not palms. And as I have pointed out there are soil types and other variables that were not completely addressed, but that is expected in science with todays funding mechanisms being what they are. Agri science chemistry is pretty good nowdays, and those I work with know I am not shy to criticize scientific efforts, its a critical part of good science that IMO is missing in much of what gets produced today.