This post is to announce a meeting on strawberry mineral nutrition to take place this coming January 30. I think it might be good to spend a little bit of time on the current salt situation as well, seeing as it is related to nutrition and water.
First presentation will be in Spanish, and the second in English, with translation provided for both.
Growers and PCA's - bring a copy soil and/or tissue sample analysis for review of sufficiencies/deficiencies/toxicities in our final exercise.
Look forward to seeing you there!
Just completed a full diagnosis with UCCE colleagues Jose Aguiar and Steve Koike of some stunted strawberry plants depicted below from the Coachella Valley. Steve's diagnostic lab found nothing, so we moved on to an analysis of the soil and tissue.
Same deal as what we have been starting to see up here; stunted plants, burnt leaf margins and dying plants. I ran the samples through a lab test, and sure enough the soil EC for the dead plants is 3.5 dS/m, for dying plants 3.0 dS/m and soil from healthy plants 1.6 dS/m. Seems the issue is one of a lack of volume and/or movement of water in the sick plots, because we see the easily leachable nitrates and sodium higher in the samples from the dead and dying plants (nitrates: 26 and 30 ppm; sodium: 345 and 299 ppm - yikes!) than from the soil around the healthy plants (nitrates: 9.7 ppm; sodium: 147 ppm).
1/2/2013 Update from tissue samples: Healthy plants (N 2.9%, P 0.52%, K 2.0 %, Mg 0.55%, Na 270 ppm, Cl 4100 ppm, Total S 0.29%, Fe 750 ppm , B 55 ppm); Dying plants (N 3.0%, P 0.47%, K 1.5 %, Mg 0.76%, Na 4500 ppm, Cl 11,000 ppm, Total S 0.4%, Fe 920 ppm , B 52 ppm). Chloride in the salty plants is up there, but does not compare to the 16x concentrations of sodium found there.
Strawberry growers across the state need to keep running that water until we get some rain. There is so much salt building up in these soils right now.
People should be super aware right now that the lack of rain we are experiencing is certain to exacerbate salt problems in berries this winter. I’ve been driving around a bit visiting fields, growers and PCA’s and the problem doesn’t yet seem too bad although I am starting to see a little bit of damage here and there. Still, I have a strong sense of foreboding that this could get big as the season progresses on the Central Coast without any rain.
See the pictures below from colleague Steven Koike for what salt damage looks like in strawberries.
Key points to keep in mind regarding winter management of salinity (Many thanks to Dr. Stuart Styles from Cal Poly in San Luis Obispo for giving me a copy of the entire data notebook of his work on salinity in strawberries from which I draw the points below - I treasure this book and it has been very useful to my understanding of this topic):
1. Salinity is a key determinant in the healthy establishment of strawberry transplants, and young plants do not tolerate elevated levels of salinity for very long. Certain literature seems to say that soil salinity EC of above 4.0 dS/m would result in total loss of fruit yield, but Dr. Style’s work demonstrates this is going to depend where exactly this salinity is to be found. His work and my own experience in the field informs us that if the grower acts quickly and the salinity is kept away from the roots, the effect on fruit yield could be much less.
2. Salts come from various sources including irrigation water, gypsum, fertilizers and especially composting (which is why I think we tend to see more salt damage in organically farmed berries).
3. Rain has a HUGE effect on soil salinity. According to the work of Dr. Styles and his colleagues, a single heavy rain can lower soil salinity by 50%; less so because of the quantity of water but because the rainwater has a low pH and zero salt content.
4. Salinity of irrigation water has a real impact on fruit yields. Water salinity of less than 1.0 dS/m will have very little impact on yield, but as the irrigation water salinity creeps over 1.2 dS/m the effect can be substantial.
Most of the Powerpoint presentations from yesterday's Fumigation Alternative Symposium are now available:
Really great meeting by the way, many thanks to the Strawberry Commission for organizing, to each of the presenters for presenting and participants for coming out and being part of it!
As we look to be in for some freezing temperatures for the next couple of days on the Central Coast, it is a good time to review what sort of frost protection would be necessary for our berry crops.
The real key right now is that pretty well our entire berry crop is free of flowers, which would be the plant organ most susceptible to freezing and subsequent loss. With some exceptions, raspberries and blackberries have dropped their leaves and are growing very little, if at all. With strawberries, there might be some concerns about newly emerged leaves experiencing some frost damage, but the temperatures being discussed right now being in the low 20’s, I just don’t see there being any freeze damage to the crown and subsequently damaging the plant for the long term.
Be that as it may, it is still good to know what to do if the concern does arise about a frost causing damage to a berry crop. I had a great discussion with my colleague Steve Tjosvold at the office this morning, and really the best option is to load the bed with water during the day by irrigating it (drip is fine), allowing the bed to accumulate heat which will then be radiated out of the moistened soil during the night, keeping the immediate environment around the plants warmer than the ambient freezing temperatures.
For fuller, in depth discussion, see the excellent summary attached below: