Summer active grass weeds

AgPest — Sat, 30 Sep 2017 19:30:17 +0000

If your run-out pasture was infested with summer-active grass weeds last summer, consider growing a forage crop for one or two summers prior to sowing the perennial pasture. This provides the opportunity to selectively spray the summer-active grasses and prevent weed seeds from replenishing the seed bank and infesting newly sown pastures. Forage crops will also disrupt clover root weevil populations allowing better subsequent establishment of young clover.

Summer-active grass weeds

AgPest — Fri, 30 Sep 2016 21:30:52 +0000

If your run-out pasture was infested with summer-active grass weeds last summer, consider growing a forage crop for one or two summers prior to sowing the perennial pasture. This provides the opportunity to selectively spray the summer-active grasses and prevent weed seeds from replenishing the seed bank and infesting newly sown pastures. Forage crops will also disrupt clover root weevil populations, allowing better subsequent establishment of young clover.

For further information on weed and pest identification, biology, impact and management visit our AgPest Online Pest Directory.

Summer grass

AgPest — Sun, 16 Jun 2013 22:45:10 +0000

Grazing

Avoid overgrazing which opens up pastures to summer grass invasion. The seed bank in the soils of many North Island dairy pastures is dominated by summer grass
Avoid moving stock from infested paddocks to clean paddocks as this increases the risk of seeds being transferred in dung.

Pasture renewal

To prevent summer grass emerging from the seed bank and infesting new pastures, it is best to prevent summer grass seed production for two years before pasture renewal
During this period it must not be allowed to set seed and replenish the seed bank. Crops such as maize, chicory, turnips or lucerne and other legumes should be used as summer grass can be easily controlled in these.

Spraying

Roadside spraying should be timed for just before Christmas when first seed heads generally emerge
Glyphosate can be used to control small isolated patches of summer grass
Residual herbicides have the potential to prevent the germination of summer active grasses.

ALWAYS READ PRODUCT LABELS BEFORE APPLYING

Active ingredient	When to apply	Residual effect	Grass damage	Clover damage
ethofumesate	When the plants are small, preferably before tillering. Spot spray only except for ethofumesate	Yes	Not to ryegrass	Severe
clethodim		Moderate	Severe	No
dalapon		Moderate	Moderate	No
fluazifop-p-butyl		Moderate	Severe	No
glufosinate-ammonium		No	Severe	Severe
haloxyfop / haloxyfop-P		Moderate	Severe	No
quizalofop-P-ethyl		Moderate	Severe	No
simazine, amitrole and dalapon		Severe	Severe	Severe

Consult your farm consultant, industry rep. or the New Zealand Agrichemical Manual for more information about chemical control.

Similar summer-growing grasses

Digitaria ciliaris, also known as summer grass, is very similar to D. sanguinalis and is found in waste and open places in the North Island but rarely in the South Island. Its leaf sheaths have hairy margins, the hairs around the collar are shorter, its ligule is irregular and the seed head has shorter branches.

Digitaria ischamum, smooth summer grass, is found on sandy or dry ground in pastures and along roadsides from the Waikato and Bay of Plenty southwards in the North Island and in Marlborough and Otago. It has hairless leaves and leaf sheaths and does not root at the nodes.

Digitaria violascens, also has hairless leaves and leaf sheaths but does not have collar hairs. It is found in waste and open places in Northland and also in the cities of Auckland, Hamilton and Tauranga.