Mintweed: pest

Page last updated: Monday, 4 May 2020 - 10:21am

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Mintweed (Salvia reflexa) is an uncommon weed in Western Australia (WA). This article describes the nature of the plant with links to control methods.

Form: herbaceous — annual

Status: present in WA

Also known as narrow leafed sage, lance-leafed sage, blue sage and sage-mint. This weed originated in southeastern United States and Mexico. In WA, it has been found occasionally near Kalgoorlie and Esperance, and in Perth.

Appearance

Mintweed is an erect summer-growing plant about 60 centimetres in height.

Stems: Square in cross-section, like most other members of the mint family. It has many branches with numerous leaves.

Leaves: Greyish and narrow with shallow toothed edges. They are arranged in pairs opposite each other on the stem and branches, and vary from two to five centimetres in length and up to 0.5 centimetres in width.

Flowers: Small, blue to lilac in colour, and approximately tubular or bell shaped. The petals have two lips, one narrow lip extended almost twice the length of the other. Flowers are usually formed in pairs opposite each other on slender spikes at the end of branches.

Fruit: Consists of four pods (or nutlets), each containing one seed.

Seeds: Fawn or cream coloured, smooth, angular, 2.5 to 3 millimetres long, 1 to 1.5 millimetres wide.

When crushed the plant has a distinctive strong mint-like odour.

The time between germination and the formation of viable seeds may be as little as six weeks, and up to four generations may take place in one season. It is very drought tolerant, germinating with little moisture and, when wilted, revives after very light showers. It rapidly invades overgrazed and badly managed pastures, particularly near sheep camps and watering points.

Agricultural and economic impact

Crop weed (cotton) and pasture weed. Mintweed invades the better soils and competes with pasture plants and, occasionally, crops. The leaves contain a chemical which, when incorporated in soil, inhibits seed germination of other plants. Seed can contaminate grain.

Potentially toxic to sheep and cattle. Stock grazing mintweed have sometimes suffered from nitrate poisoning; however, in most cases the stock that died were in poor condition and newly introduced to the weed.

Legal status

The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Search for mintweed in WAOL using the scientific name Salvia reflexa

Search > detect > report

MyPestGuide™ Reporter
via app or online
(Select 'Send report to MyWeedWatcher' from menu)
mypestguide.agric.wa.gov.au

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
padis@dpird.wa.gov.au

Control method

When using any agricultural chemicals please ensure that you always follow instructions on the label and any permit. Users of agricultural chemical products must always strictly comply with the directions on the label and the conditions of any permit.

Only registered products can be used for weed and pest control.

Control methods for this plant can be found through the APVMA website, use "mintweed" as the pest name.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080