Controlling Onion Pests and Diseases

It is particularly important to ensure that environmental and growth constraints do not limit bulb formation and bulb quality. Control of pests and diseases, will minimize rots and storage disorders.

Soil sterilization and good rotational practices are important in helping minimize disease problems. A good crop nutrition is essential to make onion and garlic crops less susceptible to pests and diseases.
There are several important pests that attack onions and garlic, like nematodes, stem and bulb eelworm, thirps and onion fly or maggot.

Onions are also very prone to foliar diseases and bulb rots, such as slimy or ‘sour’ outer scales, a bacterial disease that significantly reduces onion bulb quality.

Fungal diseases such as neck rot, mildew, rust and leaf rot, are frequent too. Fungicidal control is required on these cases.

onion sour scales
Sour scales
onion neck rot
Neck rot

Crop Nutrition and Onion Pests and Diseases

Optimum nutrient management during establishment and vegetative growth are needed to ensure nutrients don’t limit bulb quality.

Nitrogen and Potassium

Nitrogen and potassium are required to maximize bulb dry matter and size. Too much nitrogen softens the bulb and increases storage rot diseases. Excess N can also thicken the neck, resulting in greater disease entry.

Calcium

calcium and onion bulb rots

Calcium is particularly important for bulb density, integrity and long-term storage with minimal disease problems. Calcium has a major role to play in promoting long-term storage quality with minimal diseases problems. Trials confirm that onion crops with high levels of calcium in the bulbs have reduced levels of black rot due to Aspergillus niger and also less neck rots such as Botrytis allii.

Recommended Yara Fertilizers for Onions

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YaraMila COMPLEX

12-4.8-14.9 + 8% S - Prilled NPK fertilizer which also contains magnesium and sulphur as well as micronutrients ideal for use on a wide range of arable and horticultural crops.

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YaraLiva TROPICOTE

15.5% N + 18.8% Ca - Granular calcium nitrate fertilizer for field application to a wide range of crops.

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MAINCROP S

14-5.7-17.4 + 2.2% S - A quality size matched NPK plus S size matched blended fertilizer, ideal for use for potato production due to the ratio in the of N P and K whilst including a useful amount of sulphur.

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STARTER SOLUTION PLUS

A liquid fertilizer for placement which aids rapid crop establishment, promotes efficient utilization of phosphate and improves phosphate availability.

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YaraVita BORTRAC 150

A liquid micronutrient fertilizer containing 150 g/l boron for foliar application to provide additional boron or to treat boron deficiencies in a wide range of crops.

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YaraVita BRASSITREL PRO

A flowable liquid suspension fertilizer with a combination of micronutrients including manganese, magnesium, boron and molybdenum for foliar application to oilseed rape, brassicas and legumes.