Plant tissue analysis

[u/JJThompson84]

Curious what others are doing. I sample twice a year.

1. Petiole at bloom/flowering, sample position: opposite the inflorescence.

2. Petiole at veraison, sample position: about 2/3 up the shoot from the cordon. Instructions I found say "~5th leaf" from the shoot tip. Although I hedge so this isn't entirely accurate, it does allow for some consistency and the petioles are maybe the "newest matured leaf". So not old basal leaves and not brand new ones either.

Someone told me a lead blade sample can often show Nitrogen results better at veraison. A quick google says lead blades can often indicate other nutrients over petioles too...

Any tips?

[u/Copperstorm2022]

Some macronutrients are very mobile at veraison, like potassium, which is being pulled from leaf blade to fruit for a variety of uses in fruit like enzyme activation and cell expansion. Therefore, low petioles potassium is an early warning sign of ripening problems. But nitrogen is largely bound in chlorophyll molecules but may fluctuate in petioles, so leaf blade nitrogen may be a better indicator of things like vine vigor and YAN.

[u/JJThompson84 → u/Copperstorm2022]

Thanks. I had assumed to test petioles during both stages as I thought it might be more of a consistent study on how and when the plans is using nutrients. Not sure what might be classed as industry standard. Maybe both are options at bloom/veraison to monitor different things?

[u/Copperstorm2022 → u/JJThompson84]

I have always done both bloom and veraison measurements, with bloom more focused on micronutrient needs and veraison more focused on macronutrient needs. The place I work historically only does petiole samples, so I follow suit. I think veraison petiole samples are adequate to examine phosphorus, potassium, and magnesium, and while nitrogen may be more bound in leaves there are probably other indicators that let you know if you have nitrogen issues, like poor vigor and chlorosis (which are confounding traits with other problems, unfortunately, so you might need further diagnosis).

[u/breadandbuttercreek → u/Copperstorm2022]

I would be very hesitant to add potassium or nitrogen unless there was obvious deficiency. Potassium will raise your pH, in most vineyard districts this is a bad thing. Nitrogen will increase vigour, it may increase yield but at the cost of bigger berries and reduced quality. Generally it is best to avoid adding nutrients unless absolutely necessary.

[u/Upstairs_Screen_2404 → u/breadandbuttercreek]

Hence the sampling. It is important to apply fertiliser post harvest and up to 6kg/ha of Phosphorus can be removed per ton harvested. Nitrogen can increase vigour but it’s also important for a vine going into dormancy.

[u/Copperstorm2022 → u/breadandbuttercreek]

I didn’t recommend adding nutrients—I explained some examples of what you might observe in macronutrient levels in petioles vs leaf blades.

[u/JJThompson84 → u/breadandbuttercreek]

I do spray potassium bicarbonate as a fungice but ease off closer to harvest. I slray fokiar nutrients: manganese, magnesium, boron and zinc at certain times and it's been interesting watching that tissue analaysis change between bloom and veraison. As for nitrogen my tissue analysis and soil analysis show very low, next to zero. Working on building the soil health now.

[u/Upstairs_Screen_2404]

We do petioles; they need to be taken from the leaf opposite the first inflorescence up the shoot and wear gloves so your sweat doesn’t affect the result and because they’re usually fairly covered in sulphur etc. We then take leaf blades at veraison for accuracy, again wear gloves.

[u/JJThompson84 → u/Upstairs_Screen_2404]

Are veraison leaf blades taken opposite cluters or in a different shoot position? Good tip on the gloves. I try to take samples as far away from a spray run as possible as I also spray foliar nutrients.

[u/Upstairs_Screen_2404 → u/JJThompson84]

Yes, same position. If you leave pluck, it can be tricky, but just go opposite a cluster, usually take about 100-200 depending on size of the petioles. Big chonky Shiraz maybe 100, tiny Chardonnay/Cab Sauv 200.

[u/rfrasernz]

I've done petiole, sap and leaf in the past. Leaf brix measured with a refrac is also useful as the results don't take a week and you can see how immediate conditions affect the vine. I'm trialing a Senseen this year, super excited. Has anyone else used one with good results?