pest management


A spreading problem for berry farms


Yellow nutsedge has proven to be a very tough foe and the spread can bemade easier when the weed is picked up by agricultural equipment. By Grant Ullyot


t started in blueberries, but last summer the invasive weed known as yellow nutsedge was discovered in a carrot crop in the Delta area. This is pretty alarming, according to Victoria Brooks, who has sounded a warning for all berry growers to check their crops for this pest, which has been a major problem in Ontario corn fields for years.


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Brooks is a study director with the Canadian Minor Use Pesticides Program, working at the Pacific Agricultural Research Center (PARC) in Agassiz.


She explains that once established, yellow nutsedge is almost impossible to eliminate. Imported potted plants are believed to have been the source of the first infestation in B.C.


Weather is not a problem for the weed, which can grow in any climate.


It forms a little bulb and when growers work up their field the weed can be spread around, easily picked up with equipment.


NOT A GRASS


If you know for sure you have yellow nutsedge in a field do not take soil from that field and move it to another part of the farm, and don’t even cross an infested field or you risk spreading the weed.


As its name indicates, yellow nutsedge is part of the sedge family and is different from grasses. The leaves are thicker and stiffer than true grasses. The leaves are arranged in sets of three at the base.


Yellow nutsedge stems are solid and triangular in cross- section. The weed has the typical attributes of a successful problem weed; it is a perennial and can reproduce by multiple methods. It reproduces by tubers, rhizomes and seeds.


Brooks said it is an extremely hardy weed. A Delta grower put an infested area into a green cover crop for seven years and didn’t see any sign of nutsedge growth. After seven years the field was cultivated and planted to a crop and the nutsedge tubers that had been suppressed by the cover crop began to grow again. “This is not a new weed,” Brooks said. “When I took over trial work in blueberry fields in 1996, one of them


14 British Columbia Berry Grower • Spring 2016


was a trial that the late Jack Freeman had started. “When I looked at how they had laid the plots out in the first year, there was something — stakes — scattered throughout the field.


“I asked the technician who had been helping Jack why the stakes were scattered throughout the field, because when I looked at the field, it was in the beginning of its third year, and there were solid rows of yellow nutsedge. “The technician replied that when the trial started, the nutsedge was only in spots in the field so they had to scatter the plots around so they were in areas that had no yellow nutsedge. That was the first year and by the third year the yellow nutsedge worked up by the farmer had spread over the entire field.”


The bulbs are not easily seen. They grow to a much bigger size in tropical countries, where they are often eaten as a fruit. While the weed doesn’t look like normal grass, check it out to be certain.


There are herbicides that can help control and perhaps eradicate the weed in blueberries.


Basagran + Assist Oil can be applied when the nutsedge is 15 t0 20 cm tall, but only during warm weather. A second application can be applied seven to 10 days later. Sandea can be used for highbush blueberry plants that have been established at least four years. For all of the registered berry crops, red and black raspberries and loganberries, apply when nutsedge is in the 3 to 5 leaf stage. A second application can be applied 45 days later. Time between treatment and planting strawberries is 45 days.


There is also Sinbar, good on blueberries, raspberries and strawberries.


Early application of herbicides is important before tubers are produced. Established nutsedge infestations can last for years and one plant can produce up to 7,000 tubers and spread one metre per year. Pigs will eat nutsedge tubers and can dig them out of the soil and have been used to control nutsedge. For more information contact Brooks at (604) 796-6098.


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