Neem

You can get free help to control neem in Katherine.

Neem is a declared Class B and Class C weed.

Neem also has a statutory weed management plan (1.6 mb) which outlines the legal requirements for control.

Another name for this plant is Azadirachta indica.

Neem is a recently declared weed. It is now illegal to buy, sell or transport neem plants or seeds in the NT. Mature neem trees in garden settings are not the focus of management efforts and land holders will not be fined for existing plantings, however removal is encouraged. All seedlings must be removed to prevent further spread.

Neem - infestation

Identification

You should use this as a guide. There may be other plants or weeds that look similar.

If you are unsure, contact the Weed Management Branch.

Habit

These features describe the habit of this plant:

  • fast growing tree
  • 12 to 24m high.

Neem - habit

Stems and branches

These features can identify the stems and branches:

  • bark red-brown
  • cracked and flaking in older trees
  • strong root system with a deep tap root and extensive lateral roots.

Neem - stems and branches

Leaves

These features can identify the leaves:

  • compound leaves 20 to 40cm long
  • made up of 20 to 30 leaflets
  • leaflets between 3 to 8cm long
  • leaflets are vibrant yellowy green with distinctive toothed margins.

Neem - leaves

Flowers

These features can identify the flowers:

  • small
  • cream coloured
  • honey scented
  • grow in sprays to 30cm long.

Neem - flowers

Fruit and seeds

These features can identify the fruit:

  • fruit are green, ripening to yellow
  • similar to olives in size and shape.

Neem - fruit and seeds

Impact

Neem has proven to be highly invasive and competitive. Their large size and preference for wet areas means that control can be difficult and expensive. Deep tap roots and extensive lateral roots then enable neem trees to flourish, even in areas affected by seasonal drought.

Neem can have all of the following impacts:

  • invades and competes with native plant species even in intact environments
  • produces a prolific amount of seed, which are readily dispersed
  • can dominate riparian environments
  • 58% of the Territory is climatically suitable for neem establishment.

Habitat and distribution

Neem is believed to be native to the tropical woodlands of northeast India and perhaps other parts of the Indian sub-continent. Unfortunately Neem was deliberately introduced into Australia as a garden ornamental, for shade and for the production of azadirachtin, a broad spectrum insecticide.

Neem is widely spread across northern Australia where it has proliferated in many creek, river and drainage systems.

In the Northern Territory neem has become well established in the Katherine River system. It is also prevalent in the Victoria River District, Roper and Gulf districts. Neem remains a common garden plant in Darwin, Katherine and surrounding rural areas.

Spread prevention

A single mature neem tree can produce up to 50,000 seeds per year. These seeds are then spread by birds and bats that ingest the fruit. This has contributed to significant spread along waterways. Neem trees also produce suckers, which enable dense stands to develop.

You can prevent the spread of neem by doing all of the following:

  • remove neem trees from gardens and landscaping
  • follow up to control suckers which regenerate from roots
  • chip or dispose of lopped material
  • control large trees before the production of fruit - usually November to April
  • prioritise the control of seedlings
  • map large infestations to help develop a management plan
  • target infestations along drainage lines, minor infestations, isolated outbreaks or seedlings first
  • monitor areas that you have treated and watch for re-infestations.

Neem - spread

Control

Chemical control

The best time to treat neem is from March to May. Below is a list of treatment methods that can be used.

Chemical and concentration Rate Situation, method and notes
Aminopyralid 8 g/L + Triclopyr 300 g/L +
Picloram 100 g/L
Grazon® Extra
350ml / 100 L Seedling (individuals and infestations under 2m):
Foliar spray, apply when actively growing + non-ionic wetting agent required
Triclopyr 300 g/L and Picloram 100 g/L
Various trade names
350ml / 100 L Seedling (individuals and infestations up to 2m):
Foliar spray, apply when actively growing + non-ionic wetting agent required
Triclopyr 600 g/L
Various trade names
1 L / 60 L (diesel)
 
1 L / 60 L (diesel)
Seedling (individuals):
Basal bark < 5cm stem diameter
Adult (individuals or infestation):
Cut stump > 5cm stem diameter
Fluroxypyr 333 g/L
Starane® Advanced
1.8 L / 100 L (diesel)
 
1.8 L / 100 L (diesel)
Seedling (individuals):
Basal bark < 15cm stem diameter, treat up to 45 cm from ground
Adult (individuals or infestation):
Cut stump > 15cm stem diameter
Triclopyr 240 g/L + Picloram 120 g/L
Access®
1 L / 60 L (diesel)
 
1 L / 60 L (diesel)
Seedling (individuals):
Basal bark < 15cm stem diameter
Adult (individuals or infestation):
Cut stump > 15cm stem diameter
Picloram 20 g/Kg
Tordon® granules
35 to 45 g / m2 Apply granules over an area extending from the main stem to 30 cm outside
the dripline to cover the main part of the root system

Non-chemical control

Physical removal should be done before fruit grows to stop seed spread.

Hand pulling and grubbing

Weeds, including their roots, are physically pulled out of the ground by hand or using hand tools. This is an effective method of control for individual weeds and recent outbreaks that haven’t released seeds yet, but it requires a lot of labour.

Bulldozing

Bulldozers, chopper rollers or graders are used to clear large weed infestations. This leaves large areas of soil exposed so follow up control or revegetation should be considered.

Last updated: 27 October 2017