Blue pimpernel / krishnaneel (Anagallis)
A low, carpeting winter broadleaf weed with small blue flowers and paired leaves on a square stem — and poisonous to grazing livestock.
- Type
- Broadleaf weed (annual, winter)
- Life cycle
- Annual; prolific seed
- Spreads by
- Seed; crop-seed contamination
- Main harm
- Carpets & competes; poisonous to livestock
Overview
Blue pimpernel or krishnaneel (Anagallis arvensis) is a common low-growing, spreading winter (rabi) broadleaf weed of wheat, gram, mustard and other cool-season crops. It has a weak, spreading, four-angled (square) stem, small oval leaves in opposite pairs, and small, distinctive flowers that are usually blue (and sometimes a scarlet-red form), opening in bright weather. It spreads low and carpets the ground between crop rows.
By carpeting the ground it competes with the crop for moisture, nutrients, light and space, especially early, and it seeds prolifically to build a seed bank and return each cooler season. It also matters beyond the crop: Anagallis is poisonous, so heavy contamination of fodder or grazing can harm livestock. Management combines clean seed, a competitive crop, early inter-cultivation and timely broadleaf herbicides, plus keeping it out of fodder.
How to identify it
- A low, weak, spreading plant with a four-angled (square) stem.
- Small oval leaves in opposite pairs along the stem.
- Small, distinctive flowers, usually blue (sometimes a scarlet-red form), opening in bright weather.
- Carpets the ground between crop rows in wheat, gram, mustard and other winter crops.
Why it is a problem
- Carpets the inter-row ground and competes with the crop for moisture, nutrients, light and space, especially early.
- Seeds prolifically and builds a soil seed bank, returning each cooler season.
- It is poisonous, so heavy contamination of fodder or grazing can harm livestock.
- Spreads to new fields as a contaminant in crop seed.
Cultural & preventive control
- Use clean, weed-seed-free crop seed and a competitive, well-fertilised, properly-spaced crop that shades the ground.
- Inter-cultivate/hoe early to remove pimpernel while the crop is young, before it carpets and seeds.
- Prevent seed set to run down the seed bank, and keep it out of fodder because it is poisonous.
- Keep field edges and bunds clean.
Herbicide control
- Use recommended post-emergence broadleaf herbicides for the crop (e.g. 2,4-D or metsulfuron in wheat) at the correct early stage and dose.
- Choose and time the herbicide for the specific crop, and treat when the weed is small.
- Never tank-mix incompatible products, and follow label timing and rates.
- Confirm the current recommended broadleaf herbicide for your crop with your local KVK.
Integrated management
- Combine clean seed, a competitive crop, early inter-cultivation and timely broadleaf herbicides.
- Prevent seed set every season to run down the seed bank.
- Keep it out of fodder and grazing, and pair herbicides with cultural methods for durable control.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
Which low weed with small blue flowers is carpeting my wheat/gram?
A low, spreading weed with a four-angled (square) stem, small oval leaves in opposite pairs and small blue (sometimes scarlet-red) flowers is blue pimpernel or krishnaneel (Anagallis arvensis), a common winter broadleaf weed. It carpets the inter-row and competes for moisture and nutrients, seeds prolifically, and is poisonous to livestock. Control it with clean seed, a competitive crop, early inter-cultivation, and a recommended broadleaf herbicide (e.g. 2,4-D or metsulfuron in wheat) — and keep it out of fodder.
Is krishnaneel (pimpernel) dangerous to animals?
Yes — Anagallis arvensis is poisonous, so if a lot of it contaminates fodder or is grazed, it can harm livestock. That is an extra reason, beyond the yield loss from competition, to control it in the field and keep it out of hay, green fodder and grazing. So when you weed it out of a crop, do not feed the heavily-infested weedings to animals, and control it before it becomes a large part of any fodder cut.
How do I stop pimpernel coming back each winter?
Because it seeds prolifically and builds a soil seed bank, the key is to stop it setting seed and to run the seed bank down over seasons. Remove it early by inter-cultivation before it carpets and seeds, use clean crop seed, and keep field edges clean. Combine that with a competitive crop and timely broadleaf herbicides each winter. Over a few years of preventing seed set, the seed bank — and the weed pressure — falls.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.