Panic grass in southern Western Australia

Page last updated: Thursday, 27 July 2023 - 4:13pm

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Seasonal growth pattern

The panic grasses have a similar growth pattern to the other warm season grasses. They respond rapidly to out-of-season rainfall including light showers and also after rain in autumn when the temperatures are mild to warm. There can be moderate growth in early winter when the prevailing weather conditions are mild, otherwise with cool conditions and frosts during winter they are essentially dormant. The panic grasses are one of the first sub-tropical grasses to start growing in spring when the temperatures increase. They will continue growing until soil moisture is depleted, then opportunistically over summer and after the rains in autumn.

Like most sub-tropical grasses, panic grasses prefer high temperatures with maximum growth at 30-36°C/25-31°C (day/night temperature) under controlled conditions. The growth rate falls sharply when the temperature is below 18°C/13°C, with negligible growth below 15°C/10°C. 

Table 1 Soil–climate adaptation

Rainfall (estimated minimum)

>425 millimetres (mm) (>400mm south coast)

Drought tolerance

Moderate to high

Frost tolerance

Low (persistence adversely affected by combination of cold, wet soils)

Soil type

Range of soils, but prefers well drained, fertile loams. In WA has performed well on coarse-textured soils, including deep white sands

Soil fertility requirements

Moderate to high

Soil pHCa

>4.3 (est.)

Aluminium tolerance

Good

Waterlogging tolerance

Low

Salt tolerance

Nil

Ability to spread naturally

Low (can have recruitment in low density stands)

Dry matter digestibility

Av. 65% (range 57-72%)

Crude protein

Av. 11.2% (Feedipedia) varies with age of regrowth and N nutrition

Establishment

The panic grasses have very small seeds (1.2 million/kilogram) that must be sown shallow (5-10mm) with good seed-soil contact. Sow 2-5 kilograms/hectare (kg/ha) of good quality seed when sown alone or 1-3kg/ha when sown in a mixture (for coated seed use the higher seeding rates). The seed requires contact with moist soil for three days to germinate. For a perennial grass the seedlings have relatively good vigour, but require 100% weed control — refer to Sub-tropical grass establishment webpage.

Panic grass has post-harvest seed dormancy for a period of 6-8 months after harvest. Commercial seed quality can be an issue as seed quality varies widely and some seed coming into WA has high levels of post-harvest seed dormancy. Most of the sub-tropical grass seed is harvested in north Queensland and the harvest window is January to April, so seed harvested in March-April can still have high levels of seed dormancy in August-September.

The recommendation is to obtain a copy of the ‘seed certificate’ which is usually issued within a few weeks of harvest (i.e. can then estimate harvest time). Fresh seed on the seed certificate equates to dormant seed. The germination tests for bare panic grass seed use a solution containing a plant growth regulator (e.g. ethanol) which is partially effective in breaking dormancy. On the other hand, germination tests for coated panic grass seed use water.

Contact information

Geoff Moore
+61 (0)8 9368 3293