Spring is just around the corner so we need to be thinking about our strawberry fertility programs. Now is a great time to get a tissue sample. This will give you a baseline and let you know if your pre-plant fertilizer has run out. It also allows you to check and adjust boron (B) levels in the plants. Boron is important for flower bud development and should be applied through the drip tape by late January.
The sufficiency range for foliar B is 25 – 50 ppm. If you are low you need to be ready to put about 0.25 pounds of actual B per acre through the drip. Foliar applications of B are not as effective at helping with flower bud development.
Usually around February is when we will begin with our fertility program. If you applied around 60 pounds on N, P, and K per acre prior to planting then additional phosphorous should not be necessary. However if you did not then you may want to consider using a water soluble triple 20 for most of the season.
If P levels are good in the tissue you can use a combination of potassium nitrate and calcium nitrate. Potassium (K) should be applied in the pre-plant fertility and is only necessary if soil and tissue show a deficiency. Studies have shown that applying as much as 90 pounds more than the recommended K did not affect yield or quality.
Nitrogen should be applied at a rate of around 0.5 lb/A/day which comes to 3.5 lbs/week. It is beneficial to split this up based on soil type and irrigation frequency. If your soils are sandy it is recommended to inject fertilizer with every irrigation to reduce leaching. On heavier soils you can get by with less frequent irrigation and fertigation.
If you want to stay on top of nitrogen fertility management it is smart to take tissue samples once spring growth begins and continue every 2 weeks. Remove 20-25 fully expanded leaves and petioles. Separate the two and submit the samples. The petiole samples give you an indication of nitrate nitrogen levels in the plant. There are charts that you can use that track what levels should be at each week of growth. Using this methods ensures that you do not over or under fertilize.
most university labs can do the petilole analysis for nitrate nitrogen so there is no need to hunt a special lab or send them to another state. As always contact your county Agent if you have questions.