Silverleaf nightshade (Solanum elaeagnifolium) is a serious problem weed in cultivation paddocks. Once established, it is almost impossible to eradicate. The plant’s root system penetrates to a depth of more that 2 metres.
Chemical control if generally effective on new/small plants but results are sometimes unreliable on established plants because the chemicals don’t reach all of the roots (especially if the herbicide mix is stronger than the label recommendation). PLOUGHING INCREASES THE PROBLEM because the broken root parts grow into new plants. The only way control can be achieved is by preventing plants from producing seed. And, because the seeds can remain viable in the ground for 15 years, eradication is a long term project.
Silverleaf nightshade grows to a height of around 80 centimetres. Very difficult to pull out of the ground because of the root system. The flowers are purple (sometimes white) with yellow stamens – the plant is usually (but not always) armed with small, sharp prickles [see image, below right]. The round fruit (berries) change in colour as they mature, from green stripes to motley yellow and orange. Each fruit contains about 60 seeds. The fruit is spread by floodwaters, machinery, animals and birds. Sheep can carry the seed in their digestive
tract for periods of 7 days or more without affecting the germination capability of the seed.
To further confuse the identification issue, silverleaf nightshade has three common “look-alikes“: native Quena, Narrawa burr and apple of Sodom. Quena is close to the same size as silverleaf nightshade, usually (but not always) with no or very few prickles. The other two look-alikes are larger, with more and larger prickles (see images below).
EFFECT ON ANIMALS
All parts of the plant, particularly the green or ripe fruit, can be toxic to animals. Symptoms include bloating, trembling, loose faeces, nasal discharge, salivation and breathing difficulties. Cattle are more susceptible than sheep. Goats or horses don’t seem to be affected.
MORE INFORMATION: Includes “Noxious Plants of Australia”, by Parsons and Cuthbertson [Inkata Press].
(1) Non-Chemical Options: The use of strong competitive crops or pastures will give some control, quarantine the infestation and prevent seeding (sheep can carry the seed in their digestive tract for periods of 7 days or more without affecting the germination capability of the seed).
Cultivation is ineffective because most of the root pieces survive!
Chemical Options: According to NSW DPI’s excellent booklet “Noxious and Environmental Weed Control Handbook Fifth Edition”, treatments for silverleaf nightshade include:
|Picloram + 2,4-D Tordon 75 D®||650 ml in 100L of water or 15.0 L per hectare||Spot spray: Spray to wet thoroughly. Extend treated areas beyond the last plant for 1metre. Boom spray: Apply early flowering before berry set.|
|Glyphosate 360 g/L Various trade names||2.0 L in 100 L of water||Apply at early flowering to berry set stage, spray thoroughly to wet. Use only with good soil moisture conditions.|
|Fluroxypyr 333 g/L e.g.Starane Advanced®||300mL in 100L water||Delay applications until majority of shoots have emerged. Follow-up treatment will be required.|
|LOOK-ALIKES – also Solanum species|
Quena – Solanum esuriale
Tropical soda apple – Solanum viarum
Narrawa burr Solanum cinereum
|There is also another look-alike – a larger and thornier version in “Apple of Sodom” – Solanum linnaeanum (I don’t have a current image)|
IMPORTANT: USE OF PESTICIDES – ALWAYS READ THE LABEL
Pesticides must only be used for the purpose for which they are registered and must not be used in any other situation or in any manner contrary to the directions on the label. Never use a herbicide in any way contrary to the label recommendations.
DISCLAIMER: The information contained in this web site is based on knowledge and understanding at the time of writing. However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of North West Weeds or the user’s independent adviser. LRT 11/09/15