Chickpea is grown from South Asia and the Middle East to North and East Africa and Australia, mostly as a dry-season crop, often without irrigation.
And two problems decide whether that crop pays:
the pod borer, a caterpillar that eats the seed inside the pod, and Ascochyta blight, the most destructive chickpea disease in the world.
In this video: scouting by the weather, the pod borer and how to count it, control with and without a spray, then Ascochyta blight, how it spreads and how to stop it, and the look-alikes.
The advice is general and global.
Your local extension service and the product label always come first.
These two enemies like opposite weather, and that is useful.
The pod borer is favoured by warm, dry weather, with an optimum of around twenty-five to thirty degrees.
Ascochyta blight is most severe at about fifteen to twenty-five degrees,
with frequent rain or long periods of wet leaves.
So in a cool, wet spell, walk the crop for blight, especially after every rain. In a warm, dry spell at flowering and podding, walk it for caterpillars. Either way, the walk is twice a week, from the first flowers.
The chickpea pod borer is the cotton bollworm, also called the Old World bollworm. It feeds on well over a hundred crops, and it reached South America in the early twenty-tens. The moth is stout, about three and a half to four centimetres across the wings, yellowish brown, with a dark kidney-shaped mark on each forewing. It lays eggs singly, on flowers, young leaves and pods.
Each egg is a tiny ribbed dome, about half a millimetre across,
white at first and turning brown before it hatches.
The caterpillar varies from green to yellow, brown or nearly black, with lines along the body and a pale band along each side, and its skin feels slightly rough.
It grows to three and a half or four centimetres in about two to three weeks, then drops to pupate in the soil. A full generation takes four to six weeks in warm weather.
Young caterpillars feed openly on leaves, buds and flowers.
Then they bore into the pods.
A round, clean hole in the side of a pod, droppings near it, and a hollowed-out seed inside: that is the pod borer. In unprotected chickpea and pigeon pea in South Asia, losses of twenty to fifty per cent are commonly reported,
and near-total loss in outbreak years.
You cannot count caterpillars by looking down at a chickpea canopy.
Instead, lay a cloth or tray between the rows, shake or beat the plants over it, and count the caterpillars that fall, by size, per metre of row.
Do it in several places, twice a week, through flowering and podding.
Look at the eggs too: black eggs have often been parasitised, which is good news.
Pheromone or light traps tell you when the moths are flying and egg laying is starting, but a trap catch on its own does not justify a spray.
How many is too many? Field studies in Bangladesh and northern India put the action level at about one caterpillar per metre of row at podding, within a range of roughly zero point seven to one point six.
In Australia, growers calculate the threshold from the control cost and the grain price; there, one caterpillar per square metre costs about twenty kilograms of grain per hectare. Ask your local extension service for your number.
A lot of pod borer control happens before and after the crop. Sow at the recommended time, in a short window across the district, so the crop misses the peak moth flights.
After harvest, cultivate the soil, because that destroys the resting pupae.
And avoid extra nitrogen and over-irrigation,
which keep the crop lush and attractive.
In the field, put up bird perches, because insect-eating birds take a lot of caterpillars. On small plots, shake the plants over a sheet and collect the larger caterpillars by hand.
And protect the natural enemies.
Egg parasites, larval parasites, lacewings, predatory bugs and spiders kill a large share of the eggs and young caterpillars when they are not disrupted. Biological products, the pod borer's own virus and Bacillus thuringiensis, work well on young caterpillars, and neem-based products deter feeding.
This pest has a long history of beating insecticides.
Field resistance is documented to IRAC groups one, two and three A, and resistance to the pyrethroids, group three A, is very widespread.
So timing and rotation matter more than the product.
Spray only at your action level, and aim at the eggs and small caterpillars, before they are inside the pods.
Once a caterpillar is in a pod, the spray cannot reach it. The groups listed in Laisha's encyclopedia include group twenty-eight, the diamides; group five, the spinosyns; group twenty-two A; group six; group fifteen, which acts slowly on moulting larvae;
and group thirty-one, the pod borer virus where it is registered.
Never spray the same group on consecutive generations,
and follow your regional resistance strategy. Use only a registered product, at the label dose.
Now the disease. Ascochyta blight shows as round to oval tan or brown spots with dark borders on the leaves, stems and pods.
Look closely, and inside the spot you will see rings of tiny black dots.
Those dots are the fungus's fruiting bodies,
and they are the clearest sign.
Stem lesions girdle the stem, which breaks, and whole plants collapse in patches that look scorched.
Seedlings grown from infected seed show brown lesions at the stem base, and fall over. On pods, the same ringed lesions lead to shrivelled, discoloured seed, and that seed carries the fungus into the next crop. In cool, wet seasons, losses range up to complete crop failure.
The fungus survives between seasons in two places:
infected seed, and old chickpea stubble, which stays infectious for one to two years or more. In the field, rain splashes spores from infected seedlings or stubble onto nearby plants, and every rain event can start a new cycle.
Leaves need to stay wet for several hours for infection,
and new lesions appear in about five to ten days. Where the fungus also forms its sexual stage on old stubble, airborne spores can travel several kilometres into new fields.
Because the fungus lives in seed and stubble, prevention does most of the work.
Plant tested, disease-free seed, treated with a fungicide seed dressing. Leave at least three to four years between chickpea crops in the same field, and plant away from last year's chickpea stubble. Bury or remove infected stubble where erosion risk allows,
and control volunteer chickpea plants. Avoid very dense stands, and very early planting in high-risk areas.
Grow a moderately resistant variety where you can: it greatly reduces the sprays needed. But the fungus adapts, so check the ratings each year.
Inspect the crop a few weeks after emergence and after each rain, starting near old stubble. There is no numeric threshold: protection is preventive.
Protectant sprays go on before rain in susceptible varieties,
and systemic products after infection events. The groups in Laisha's encyclopedia are FRAC M five, the chloronitriles, and M three, the dithiocarbamates, both multi-site protectants; group three, the demethylation inhibitors;
and group eleven, where resistance has been reported in some regions, so use it only in mixtures.
Base the programme on the multi-site protectants, and use registered products at the label dose.
Not every hole or brown patch is what it seems. On cowpea and pigeon pea, a different caterpillar, the legume pod borer, webs flowers and pods together with silk;
it is pale with rows of paired dark spots.
Pod-sucking bugs leave shrivelled pods and seeds with tiny punctures, but no holes or droppings.
For the disease, grey mould is a grey, fuzzy growth on flowers and stems in dense, humid canopies, with no rings of black dots.
Fusarium wilt yellows and wilts plants from the base, often on one side, with brown discoloration inside the stem and no spots.
Frost or herbicide damage is uniform, with no lesions.
To recap.
Warm and dry means caterpillars; cool and wet means blight.
Scout twice a week from the first flowers.
Beat the plants over a cloth and count caterpillars per metre of row;
about one per metre at podding is the South Asian action level.
Sow in a short window, cultivate after harvest, and protect the natural enemies.
If you spray, hit eggs and small caterpillars, and rotate groups. For blight, start with clean, treated seed, keep three to four years between chickpea crops, stay away from old stubble, and protect before rain.
For the full chickpea guide and the pest and disease encyclopedia, visit laisha.ai.
And before you go: Laisha Lens number one is out, our free guide to November, for every climate zone on Earth.
North of the equator, the cool-season crops go in:
winter wheat and garlic in the temperate north,
wheat, barley and lentil on the autumn rains of the Mediterranean,
and on the plains of South Asia the whole rabi season,
wheat, mustard, chickpea and potato.
South of the equator it is spring, and the tropical south sows soybean, maize, cotton and rice on the first rains.
Lens also covers crop residue without fire, the pests worth walking the field for, and a study plan for agri students.
Open My farm's November, choose your zone and up to three crops, and it builds your field jobs, week by week, with the pests to scout for. It is free, and needs no account. Our free November Lens, with your farm's month plan, is on laisha.ai slash lens.
From all of us at Laisha: may your fields do well this season. Thank you for watching.
