If your vines have poor fruit set or low volume harvests, its often due to either soil nutritional deficiencies (or inadequate irrigation). A leaf/petiole tissue analysis is the best way to determine if your soils are low on nitrogen, or macronutrients (calcium, phosphorus, magnesium, potassium) or micronutrients (zinc, manganese, boron, copper, iron, sodium). Vines need at least sufficient quantities of all of these nutrients to produce properly. Plus, the next LWGA meeting on Sunday, June 6, will include an overview of leaf/petiole tissue results and how to resolve soil nutritional deficiencies, so if you get your samples in asap, you may have the results in time for this meeting.
Now, at bloom, is the best time of year to do a tissue nutrient analysis. Here are general instructions for Fruit Growers Labs, the company I have used and just sent in this year’s samples for testing. There are other labs that do this testing as well, such as www.al-labs-west.com/ (which appears to be lower priced)
For FGL, request the comprehensive petiole group. Make sure to collect your samples in the morning, and cut
the stems (petioles) of the leaves right away otherwise nutrients can
flow from petiole to leaf, and brown bag them in separate bags instead
of using ziplocks. I send them in one usps priority mail box instead
of overnight because overnight is so expensive. If you use priority
mail, get them to the post office before noon on either monday or
tuesday so they get to the lab before the weekend, and send them to
the Santa Paula address. Instructions and forms are on their website, or see links below.
