Evergreen Huckleberry

Root rot is not one organism but a group of soil fungi and water molds - Pythium, Phytophthora, Fusarium, Rhizoctonia and others - that sit harmlessly in most soils and only turn destructive when the ground stays saturated. Waterlogged soil drives the air out, the roots suffocate, and the weakened tissue is invaded and goes soft, brown, and stringy. Because the damage is underground you usually see it first as something that looks like drought: wilting, yellowing, stunting, a plant that does not respond to being watered. Overwatering, heavy compacted ground, a low spot that collects runoff, a pot with no drainage or a saucer left standing full, and cold wet soil in winter are the usual causes. Once roots have actually rotted there is no cure - this is a problem you prevent rather than treat.

Watch for: Wilting in the middle of the day on a plant whose soil is damp - the classic tell, and the reason people water a rotting plant and finish it off. Leaves yellowing from the bottom up, dull off-color foliage, and growth that stalls for no visible reason. Whole shoots, or one side of the plant, collapsing while the rest still looks fine. Soft, dark, or mushy tissue at the base of the stem or at the crown, sometimes with a sour smell. Lift a failing plant and look at the roots: healthy ones are firm and pale, rotted ones are brown or black and slimy, and the outer layer slips off between your fingers leaving a thread of core behind. Seedlings that topple over at soil level are the same problem, called damping-off.

Prevent: Drainage is the whole defense. Match the plant to the site first - something that wants sharp drainage will not survive heavy clay or a low, water-collecting spot however well you tend it. Where the ground is heavy, plant on a raised bed, berm, or slope, or grow in a container. Set plants at the depth they were already growing, since burying the crown or the root flare is a common cause of rot, and keep mulch pulled back a few inches from the stem base instead of piled against it. Water the soil rather than the calendar: check that the top inch or two is dry before watering again, cut back hard in cool weather and winter dormancy, and never leave a pot standing in a full saucer. Do not plant or dig in soggy ground, and go easy on rich amendments for plants that want it lean. Rotate annual crops, and start with clean healthy plants and fresh mix.

Treat: There is no cure for tissue that has already rotted, so act on the conditions rather than looking for a spray. Stop watering at once and fix the drainage - open up compacted soil, or move the plant to a raised, sharply drained position or a container. Lift a badly affected plant, cut away every soft dark root and rotted section with a clean blade back to firm pale tissue, and replant only the healthy parts into fresh free-draining soil or mix. Often the better move is to give up on the plant and save its offspring instead: cuttings, offsets, or divisions taken from firm healthy growth root readily and give you a clean start. Bin the rotted material rather than composting it, and correct the drainage before you replant, because the rot comes straight back in the same wet spot.

Wants acidic, humus-rich, well-drained ground and will not tolerate a wet low spot. Raised or bermed beds help on heavy soil. Hard to reverse once established, so ease off watering and replant survivors into better-drained acidic ground.

Not an infection but a nutrient lockout caused by soil chemistry. Iron is abundant in almost every soil, but as pH rises it converts to forms roots cannot take up, so a plant that needs acid ground slowly starves for iron while standing in soil full of it. The symptom is unmistakable: new leaves go pale yellow or cream while the veins stay green, giving a fine green net over a yellow leaf. It shows first and worst on the newest growth, because iron does not move around inside a plant to be recycled. It does not spread between plants, does not respond to fungicides, and does not resolve on its own - left uncorrected the plant grows less each year, leaves get smaller and paler, shoot tips die back, crops fall away, and it eventually dies. Worst near concrete, mortar, paths and limed ground, and in cold, wet, compacted soil.

Watch for: Yellow leaves with a distinct network of green veins, worst on the NEWEST growth at the shoot tips - that vein pattern is what separates it from a nitrogen shortage, which yellows the oldest leaves uniformly. Whole plants going progressively paler over a season rather than suddenly. Brown scorched leaf margins and shoot-tip dieback in advanced cases. Symptoms concentrated on the side of a plant nearest a foundation, wall, path, driveway, or a stretch of limed lawn. One plant affected while a neighbor that does not need acid soil looks perfect.

Prevent: Test the soil pH before you plant, not after, and match the plant to the ground - an acid-loving plant in limy soil will never be truly healthy however it is fed. Where the pH is too high, acidify with elemental sulfur worked in the season BEFORE planting, since sulfur takes months of soil biology to work and cannot be rushed, and retest before you commit plants. On genuinely alkaline ground the honest answer is often a raised bed of acidic mix, or a container, rather than fighting the native soil forever. Keep an acidic organic mulch topped up - pine bark, pine straw, sawdust - and site acid-lovers away from concrete foundations and mortared walls, which leach lime for decades. Never apply lime, wood ash or mushroom compost where the roots reach, use acid-forming fertilizers such as ammonium sulfate, and improve drainage, because cold waterlogged soil hurts uptake even at the right pH.

Treat: Correct the soil, and use iron only to buy time. Chelated iron sprayed on the leaves or drenched into the root zone greens a plant up within a week or two, but it wears off in a season and has to be repeated indefinitely - it fixes nothing. The real fix is lowering pH with elemental sulfur applied to the surface and watered in, retesting each season until you are in range, then holding it there with acidic mulch and acid fertilizer. Expect one to two years; there is no fast route. Note that other shortages look identical - manganese deficiency produces the same yellow-with-green-veins pattern on some plants - so a plant that does not green up from iron should be tested rather than dosed again. Where the pH is high because of nearby concrete or genuinely calcareous subsoil, the plant is in the wrong place, and moving it into a properly built acidic bed or container will succeed where years of amendment will not.

Like all Vaccinium, evergreen huckleberry needs genuinely acidic soil, roughly pH 4.5 to 6, and declines steadily in alkaline ground. Acidify a season ahead of planting and keep an acidic mulch on it.

Root weevils - black vine weevil and its relatives - do their obvious damage as adults and their serious damage underground. The adults are flightless, dull black or grey, about a quarter to a third of an inch long with a short snout; they feed only at night and hide in mulch and leaf litter by day, so most gardeners see notched leaves for weeks before ever seeing the insect. The larvae are small white legless grubs with tan heads that live in the soil, eat fine roots, and then strip the bark from the root crown itself, which is what actually kills plants. Males barely matter - the females reproduce without them, so one insect can start an infestation. Container plants and newly set shrubs suffer most, because a small root system has nothing to spare.

Watch for: Neat crescent-shaped notches chewed into leaf margins, appearing overnight and building up through summer - unmistakable once you have seen it. Damage with no insect in sight during daylight; go out after dark with a flashlight and you will find the adults feeding. Wilting, dull foliage, or an unexplained slow decline in a plant whose leaves are also notched, which is the combination that points at larvae on the roots. Container plants that loosen in their mix or lift out with almost no fine roots left. Chewed, girdled bark at the root crown just below soil level on a young shrub that has collapsed.

Prevent: Check new plants before you buy, since weevils travel in nursery containers and that is how most gardens acquire them. Keep deep loose mulch and leaf litter pulled back from the base of vulnerable shrubs, because that is where the adults shelter through the day. Keep plants vigorous and steadily watered so root feeding is easier to shrug off. A sticky barrier band around the base of a container, or a smooth-sided pot, stops the flightless adults climbing back up. Encourage ground beetles, birds, and shrews by leaving some rough ground, and avoid broad-spectrum insecticides, which do nothing about the larvae underground and remove the predators that eat the adults.

Treat: The notching itself is cosmetic and needs no treatment on an established plant, and spraying for the adults is largely wasted effort since they feed at night and hide by day. The larvae are the target. Drench beneficial nematodes into moist soil in late summer or early autumn while the grubs are small and the soil is still warm - that is the single most effective home control and it works especially well in containers. Repeat the following year if damage continues. Hand-collect adults after dark from small collections of plants. Repot badly affected container plants into fresh mix, washing the roots and removing every grub you find, and cut your losses on a shrub whose root crown has already been girdled.