Fava Bean

Cold, soggy soil at sowing and establishment is the whole risk on favas. Sow into well-drained ground, avoid replanting the same wet spot year after year, and rotate.

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.

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.

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.

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.

Search for this as 'chocolate spot' - it is the fava disease to watch in a cool, wet spring, and the reason airflow and dry foliage matter more here than in a summer bean.

Reddish-brown to chocolate-coloured flecks on leaves first, spreading to stems and pods; spots enlarging into sooty blotches, blackened stems, and fuzzy gray mould in prolonged damp, still weather.

Remove badly affected growth, open the stand up for airflow, and harvest ahead of prolonged wet spells; a labelled fungicide only where pressure is high. Do not compost heavily infected debris.

Space plants and thin dense blocks for airflow, avoid excess nitrogen and soft growth, water at the base rather than overhead, keep the bed weeded, make sure drainage is good, and rotate away from where favas grew.

The signature disease of fava and broad beans, caused mainly by Botrytis fabae: reddish-brown 'chocolate' speckles peppering leaves, stems, and pods, which enlarge and run together into dark blotches in a cool, wet spring. In a bad aggressive phase it blackens whole stems and can collapse a crowded stand.

On favas rust often shows up as the weather warms near the end of the season, when the crop is winding down anyway, so it frequently costs nothing.

Small raised rusty-orange pustules ringed with yellow, mostly on the leaf undersides and usually starting low in the plant where humidity is highest, followed by yellowing, browning and early leaf drop once it takes hold.

Strip the worst-affected leaves early, starting with the lower ones. Sulfur slows the spread in a wet season; copper is not effective against rust. A late infection often still allows a full harvest, and fungicides are rarely needed in a home garden.

Grow resistant or tolerant varieties where they are offered, space and train for airflow, water at the base so the leaves stay dry, and rotate beans on a two to three year cycle. Remove crop debris after harvest rather than leaving it to carry the fungus over.

A fungal disease (Uromyces) of bean-family plants, producing raised rusty orange-brown pustules on the leaves and sometimes the stems, mostly on the undersides and ringed with yellow. Heavy infection browns and drops the foliage, and losing leaf area during pod fill directly shrinks the crop. It is worst in warm, humid weather and wherever the leaves stay wet.