Almond

Dial irrigation back as hull split starts, to starve hull rot

Reduce irrigation at the onset of hull split and never leave standing water under the trees while hulls are open. Keep nitrogen off the tree in the 45 to 60 days before hull split; if you leaf-sample in midsummer, nitrogen should read below 2.6 percent. Rhizopus stolonifer and Monilinia colonize the wet, sugary hull the moment it splits, and a lush, over-watered, over-fed tree keeps that hull moist for weeks instead of days. Hulls stay susceptible from split until they dry - anywhere from 10 days to 2 months, and irrigation and nitrogen are what decide which.

⚠ Do not cut water on a tree that is already drought-stressed, and never apply oil sprays to water-stressed trees. If you are also spraying for navel orangeworm at hull split, a Rhizopus-targeted fungicide tank-mixed at that timing cuts hull rot 60 to 70 percent.

Feed lightly in spring, after leaf-out

Start after leaf-out, not before. For a home tree, apply about 1 ounce of actual nitrogen per year of tree age, capping at roughly 1/2 pound per year for a mature tree. Split it across the season rather than dumping it at once, and water it in deeply and infrequently. Nitrogen applied between late fall and spring is mostly gone before the tree leafs out and can take it up, so it leaches past the roots instead of feeding the crop. Fed too heavily, almond grows wood instead of nuts.

⚠ Excess nitrogen is a real cause of a healthy-looking almond that will not set nuts, and late-season nitrogen after the kernels have filled goes into the hull, where it raises hull rot risk rather than yield.

Dormant pruning: build the frame early, then leave it aloneJan – Dec

Prune after leaf drop and before bud swell. At planting, head an unbranched whip at 30 to 36 inches above the soil to force low scaffolds; on a branched tree, remove anything below about 30 inches and keep 4 to 6 evenly spaced branches. A mature almond needs very little pruning - take out dead, broken, and crossing wood and open the center enough for light and spray coverage. Almond puts its structure on in the first few years and then coasts, so the framework you select early is the one the tree carries for decades. Heavy cutting on a bearing tree removes the spurs that carry the crop.

⚠ Prune in dry weather and finish before bud swell - almond blooms extremely early, and in warm zones bud swell can arrive in January. Fresh cuts are most vulnerable to canker fungi in the first weeks, so avoid pruning just ahead of a rain.

Dormant oil for scale - and the job that beats itNov – Dec

Once the tree is genuinely dormant, narrow-range oil smothers overwintering scale and mite eggs. But do the sanitation first: strip and destroy every mummy nut left on the tree, because that is where next year's navel orangeworm is living right now. Removing mummy nuts in fall or winter, and harvesting early with prompt removal of nuts from the orchard floor, are the two things UC IPM calls essential to navel orangeworm control - the spray is not.

⚠ PHI IS THE WRONG THING TO CHECK FOR A NOVEMBER SPRAY: harvest is nine months away, so any label interval (0-28 days) is satisfied many times over. What actually binds is the tree being dormant, not spraying oil during or near bloom, and not spraying on freezing or wet days. Dormant-timed insecticides also raise winter runoff concerns. The PHI that DOES bite on almond is at hull split in July-August: spinosad 1 day, Bt 0.

Brown rot blossom blight: fungicide at pink bud and full bloom

Spray propiconazole, or pyraclostrobin plus fluxapyroxad, at pink bud (5 to 10 percent bloom) and again at full bloom. In a dry year a single full-bloom application is usually enough; a long bloom with rain warrants the second. Monilinia laxa overwinters in twig cankers and old infected flowers, and its spores blow or splash onto open flowers during wet weather. It infects through the flower itself, so the fungicide has to be on the petals before the rain, not after the blossoms brown.

⚠ This is a fungicide, not an insecticide - never add an insecticide to a bloom spray, because hives are in the orchard and bees are working the flowers. Rotate modes of action: make no more than one application of FRAC group 1, 4, 9, 11, or 17 before switching to a different group, or you will select for resistant Monilinia.

Shot hole at petal fall - but only if last fall's leaves told you to

Look at last autumn's leaf lesions with a hand lens: if the tan spots carry tiny black fruiting bodies, spray at petal fall this spring with iprodione, or azoxystrobin plus propiconazole, and continue at label intervals while wet weather lasts. If you found no fruiting structures, skip the spray. Wilsonomyces carpophilus needs prolonged leaf wetness to infect, and the black fruiting bodies on old lesions are the inoculum that starts the new season. No fruiting bodies means no spore source worth spraying against.

⚠ These are protectant fungicides, not eradicants - they only work if foliage is covered before the wet period begins, so spraying after a rain is wasted product. Follow your product's label for the per-season cap: UC IPM sets these per product, not across the board - some QoI/SDHI products allow only two applications per season, others three or four. Rotate modes of action, and note that iprodione is FRAC group 2, so it does not count against a QoI or SDHI limit.

Navel orangeworm: hit the first 1 percent of hull split

Cut small branches from the top southwest quadrant of 5 or 6 trees and watch for the first hulls to split. At the very beginning of hull split, and no later than 1 percent split, spray methoxyfenozide, chlorantraniliprole, spinetoram, or Bacillus thuringiensis. Under heavy pressure, repeat 2 to 3 weeks later as the crop finishes splitting. The hull is the tree's own armor; the instant it cracks, the kernel is exposed and navel orangeworm moths lay directly into the opening. Spray a week late and the larvae are already inside the shell where nothing can reach them.

⚠ Pre-harvest intervals differ sharply by product and harvest is only weeks away - check your label and count back: chlorantraniliprole is 10 days, methoxyfenozide 7 days, spinetoram 1 day, and Bacillus thuringiensis 0. Use a reduced-risk, non-pyrethroid product: pyrethroids like bifenthrin kill the predatory mites and touch off spider mite outbreaks, and their residues stay toxic to beneficials long after application. If bees are still present, apply spinetoram or spinosad in early morning or evening only.

Frost watch: almond blooms first and pays for it

Track overnight lows through bloom. Open flowers are killed at about 28 degrees F, so cover small trees with row cover or blankets on radiation-frost nights and uncover in the morning. Plant on a slope or high ground where cold air drains away rather than in a low frost pocket. Almond is the earliest stone fruit to bloom, often weeks before the last frost, and a flower killed at 28 degrees F is a nut that never forms - the whole crop can be lost in a single clear, still night.

⚠ Winter lows below about -10 degrees F damage fruit buds outright, which is why almond fails as a crop in cold-winter regions no matter how the bloom is protected. Remove covers each morning so bees can work the flowers.

Shake as soon as the nuts will come off

Nuts ripen unevenly - the upper, outer southwest quadrant splits first and the eye-level interior nuts are the laggards. Wait until 95 to 100 percent of the fruit at eye level is visibly split, then shake or pole the tree and get the nuts off the ground promptly. Dry them until the kernels snap rather than bend, then store airtight. Every day a split nut hangs on the tree, or lies on the ground, is another day navel orangeworm can lay into it. Early harvest with prompt pickup is one of the two cultural practices UC IPM calls essential to controlling that pest - it does more than any spray.

⚠ Nuts left on the tree over winter become mummies, which is exactly where next season's navel orangeworm overwinters - strip and destroy them rather than leaving them.