Wet or Dry, Get Ready for Bloom

Franz Niederholzer, UCCE Farm Advisor, Colusa/Sutter/Yuba Counties

Spring isn’t here yet, but it will be before we know it. What happens then, weather-wise, and how you react to those conditions could change the season for your operation. But, no one can be certain of the weather this spring. Will it be wet? The forecasters think there is a good chance for that. If that’s the case, more bees and bloom sprays, and less irrigation will be needed. But, they could be wrong and 2016 could be another dry year. Better plan for a wet or a dry spring.

Here are some things to consider:

Topic Wet Dry
Bees Higher hive stocking rates (3 hives per acre, minimum of 6-8 frames, with one frame of brood) are recommended in wet years. Spray carefully. No difference from the last few years. Make sure bees have water sources and fungicides are applied with bee health in mind. Click HERE1 for link to Almond Board BMPs for bees.
Bloom sprays With rain at bloom, UC recommends 2 bloom sprays – pink (5% bloom) and full bloom. If it is warm at bloom, use material(s) with anthracnose activity. If it continues to rain, more fungicides will be needed. The more fungicides used, the greater the need to rotate chemistries. Click HERE2 to see info on fungicide efficacy/timing/resistance management. One bloom spray, timed before or at full bloom will provide good disease control under dry (no rain) bloom conditions.
Weed management Properly selected and applied preemergent herbicides, sprayed before rain saturates orchard soils, provides weed control when you can’t get into too-wet orchards. Pre or post emergent sprays will control weeds. Don’t fall behind. Controlling weeds saves water.
Nitrogen management 20% of annual N budget should go on by mid-March. If it’s still raining after petal fall, fertigating, which adds more water, could keep soils cold and wet. Consider banding dry fertilizer (urea, etc.) ahead of forecast rain instead of adding more water to wet soil with fertigation. Deliver 20% of annual N budget by mid-March. Fertigation should work well if trees need water, too. Don’t over-do it. Excessive irrigation in the spring can harm root health.
Irrigation Wait, unless you like yellow trees. Don’t over-do it with spring irrigation. Deliver only enough water to replace crop water use (ETc) plus any leaching fraction. Know your irrigation water quality and make sure your system is delivering as uniformly as possible.
Pest management Sanitize orchard before end of January and destroy mummies by March 1. Wet weather should hold off the insect and mite pests, but don’t stop monitoring. Sanitize orchard before end of January and destroy mummies by March 1. Look for adult leaf footed bugs in March and start scouting for mites early.
Crop yield Wet January and warm low temps = light crops. Click HERE3. to see supporting article. Another good year if you have clean water…


  1. http://ipm.ucdavis.edu/PDF/PMG/fungicideefficacytiming.pdf
  2. http://californiaagriculture.ucanr.edu/landingpage.cfm?article=ca.v060n04p211&fulltext=yes



Print Friendly, PDF & Email

2 thoughts on “Wet or Dry, Get Ready for Bloom

    1. Stan,
      I am unsure of your exact question, but I think it may be that you want to know how late one can apply dormant oil and copper and not damage the tree. This depends on the rate and type of oil. In general, as the buds begin and generate green tissues (green tip), the oil rate should be reduced and the copper should be removed. At delayed dormant, 6-8 gallons could be used, and this should be cut in half. Also, a more refined oil (e.g. 415) will reduce damage in comparison to a heavier dormant oil (e.g. 470).

      Work with copper and oil from scab control showed that the treatment was effective with 4 gallons of oil. Copper, however, is phyto-toxic to green almond tissues and it should not be considered for use once the trees break dormancy unless at very low rates.


      Hope that helps,

Leave a Reply

Your email address will not be published. Required fields are marked *