The impact of weeds

When planning a weed eontrol management plan it is important to eorrectly identify the weeds, rrrrderstarrd their life cycle, how competitive they are, ineidenee of herbicide resistance as well as importance for biodiversity. 

There are a number of reasorts why some plant species have been more successful as weeds than other plants. 

Key small amount of germination possible some germination main germination period. 

As well as being able to multiply in one field, weeds can spread from field to field. Before the implementation of some of the current very strict seed standards one important method of spread of some weeds such as wild oats, com cockle and cornflower was in the seed. These weeds set their seed at the same time as the cereal crop is harvested. The weed seed was then resown with the cereal seed. Commercial seed is now virtually weed free but weed seed can still be spread around fields by farm machineiy or in straw. Other methods of spread include wind, water and birds, depending on the characteristics of the seed. Some seed, such as of docks, can remain viable in slurry for many weeks and so can be spread around the different fields where the slimy is applied. 

Continuous cropping of the same crop, sown at the same time each year, will tend to encourage those weeds that germinate at the same time. Examples include autumn-germinating bromes and black-grass in winter cereals, and late spring/ 

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The impact of weed control in organic production must not be underestimated. In vegetable production particularly, weed control will often pose more of a challenge than pest or disease control. It is the cost of controlling weeds that can have a significant effect on the economics of organic vegetable production. 

Crop seed rates. High seed rates and good crop establishment all help to reduce the impact of weeds. 

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