What's causing the edges of my blueberry leaves to burn?

Question

Last year, this Sunshine Blueberry plant was doing stupendously - not a burned leaf in sight. Now most of the leaves appear like they're burning. Also, the fruit never mature to full size before they shrivel. I'm not even sure if those flowers are pollinated because they just look like blue versions of its flower and the weather is not hot enough for bees to come out. What's causing this?

• California Bay Area zone 9
• Water it once per week because the weather is still cold.
• It's in a terra-cotta pot.
• Temperatures have been on average 65 F during the day and 45 F during the night.
• Haven't fertilized it this year yet. I'm waiting until the weather warms up. Last year, I used cottonseed meal to make the soil acidic.

Answer 1

It's possibly a potassium deficiency. Deficient plants sometimes have yellowing around the leaf edges. Potassium is important for fruit size (so I imagine it could be a factor in fruit development). Too much nitrogen can inhibit potassium. So, be careful about that.

On the other hand, it could be a virus of some kind, but my guess is a nutrient imbalance. I would recommend a soil test if you can get one.

Here's a potassium-deficient blueberry plant.

Answer 2

Although I agree with Shule 100%, calcium is another deficiency that can cause brown leaves...I think yours is potassium deficient as well, but don't forget your calcium as well. It is perhaps the most under-noticed, yet one of the most important nutrients for your plants. Bone meal is one of the sources

Answer 3

It could be too much salt...is there a white coating on top of the soil? On the outside of the pot? Are you using tap water to irrigate? If so, repot this plant in fresh, sterilized potting soil. Water with distilled water. I've seen so many plants with leaves like this and all of them were in pots with salt-buildup. Send a few more pictures...get potting soil that has bacteria and mycorrhizae(sp) included. No rocks on the bottom below the soil, raise the bottom of the pot so there is air beneath and drainage is optimum. Water to soak completely and don't water again until the soil is dry or the pot is light. Blueberries are bog plants and love water but in such an enclosed and limited space never allow the soil to stay wet, or the pot to sit in excess water in the saucer.