sawfly damage in wheat
Providing trusted, practical education to help you solve problems, develop skills and build a better future. Spring wheat is the preferred host for this insect, however, recent reports from Alberta and especially Montana indicate that some varieties of winter wheat are also suitable hosts for this pest. They have a brown head and a short blunt projection on the rear end. 4) than other stem-boring insect larvae (e.g. No-till has been linked to many of the recent wheat stem sawfly problems in the region. At maturity, the larvae can reach a length of about 13 mm (1/2 in). I received several phone calls in July from wheat growers that had decent stands of wheat at flowering only to find fallen tillers the week of harvest – the hallmark of wheat stem sawfly damage. As the current-year sawfly larvae will survive and still consume plant matter, benefits of parasitism will not be realized until the following and subsequent years. 3 to two per cent, five per cent and 10 per cent respectively. The Government of Saskatchewan does not warrant the accuracy, reliability or timeliness of any information translated by this system. However, only one larva will survive in each stem due to cannibalism. ©2021, Colorado State University Extension, Fort Collins, Colorado 80523 USA. Feeding by wheat stem sawfly larvae reduces the plant’s vascular efficiency and results in fewer kernels per head and lower kernel weight. 1 CWRS, No. Spring wheat was the primary cereal grain impacted by this pest but it has subsequently infested and severely affected winter wheat as well. To some degree, the adoption of conservation tillage practices that leave stubble containing sawfly larvae intact may also favour increased wheat stem sawfly populations. Sawfly larvae (Figure 2) are cream colored, have a broad head, and are ½ to ¾ of an inch in length when fully grown. Although the sawfly may lay eggs in other cereals, including barley, oat, and rye, larvae rarely mature in barley and rye and do not survive in oat. Non-Discrimination Statement | However, the advantages of controlling the sawfly with tillage must be weighed against the considerable benefits of no-till. Wet conditions also assist in softening the plug in the stem allowing for easier emergence of the adult sawfly. This minimizes the amount of field border adjacent to stubble where sawfly adults will be emerging, and thus, the part of the field most vulnerable to infestation. Four sawflies in 10 sweeps results in about 23 per cent cut stems. In preparation for over-wintering in the stubble, the larvae plug the stem with frass (larval feces) and plant material (Fig. Delayed planting of wheat may be of some benefit to reduce sawfly damage, but yield and quality may also be affected. The wheat stem sawfly (Fig. It seems to be slowing moving toward northwest Kansas, so we need to be on the lookout for the adult and it’s damage in our wheat. Remember that a resistant variety will sustain damage in certain years or in certain environments. Using solid-stemmed cultivars and cultural controls are currently the most effective alternatives. The presence and effectiveness of natural enemies in Colorado has not been determined. The availability of several adapted solid-stemmed wheat cultivars provides a viable management option for parts of the northern High Plains. Find services and information for Saskatchewan residents and visitors. It is wasplike in appearance, with a shiny black body with three yellow bands around the abdomen. Early swathing, once kernel moisture drops below 40 per cent, can help to salvage infested stems before they fall and are more difficult to pick up. This maximizes the larvae’s exposure to the late summer dryness and winter cold, increasing mortality. Stem strength and stand density may also be factors in affecting crop loss. Barley is not normally a host for the sawfly. Review all public health measures. In the absence of severe sawfly pressure, producers tended to choose wheat varieties that offered attributes such as increased yield, protein and disease resistance rather than sawfly resistance. The wheat stem sawfly is an insect that girdles the stem of wheat plants and causes the plant to lodge just prior to harvest. The sawflies will oviposit in the trap crop, but the larvae will be unable to complete development. Grass sawfly larvae hatch and feed on the lower leaf blade in early May. Lancer, Leader and other varieties: AC Eatonia and AC Abbey are solid-stemmed and are considered to be resistant varieties. These translations are identified by a yellow box in the right or left rail that resembles the link below. Select a resistant variety such as AC Lillian. 2 and No. Excessively wet conditions tend to be detrimental to both sawfly and parasite populations and activity. Shallow, fall tillage can result in 90% sawfly mortality. The Sawfly insect attacks the stem of the plant hence stopping the flow of nutrients to feed the kernel. The wheat stem sawfly was not a significant pest for a number of years. It also feeds in several hollow-stemmed non-cultivated grasses, including quackgrass, smooth brome and various wheatgrasses. The legs are yellow. This method is especially effective when sawfly abundance is low to moderate and significant infestations are limited to the field margins. An adult sawfly is shiny black with three yellow bands around the abdomen. CSU A-Z Search If seed source is an issue, spread out resistant variety as much as possible by seeding borders (trap cropping) of fields to the resistant variety. Tillage reduces wheat stem sawfly survival, however, its impact on overall sawfly abundance and on damage to the next wheat crop is variable. wheat stem maggot) when removed from the stem. Enter: Bracon sephi, an orange wasp that is less than a quarter inch long. Adults will typically emerge in late-June and the first week of July. A sweep net can be used to sample for adult sawflies. The insect is found across much of western North America though damage to wheat occurs primarily in Montana, the Dakotas, western Nebraska, eastern Wyoming, and the Canadian Prairie Provinces. The wheat stem sawfly map is based on cut stem counts conducted in the fall of 2019 and the damage ratings are based on 90 fields in 21 municipalities. 1998). The program at Colorado State University also is initiating long term research into novel methods for making the wheat plant less attractive to the sawfly. grains, the host range of the wheat stem sawfly expanded and wheat was found to be a viable and easily accessible host. Durum wheats are semi-solid and are rarely attacked by the sawfly. Infested plants will have reduced yield and test weight and produce shriveled grains; mature larvae may or may not girdle plants at their base, inducing lodging. Solid stemmed varieties are filled with pith, especially in the lower parts of the plant. The larva will most likely be located in a chamber within the stem, just above the crown. This may help reduce larval numbers, but it is not recommended as a good agronomic practice and will also greatly reduce beneficial parasites. The name is associated especially with the Tenthredinoidea, by far the largest superfamily in the suborder, with about 7,000 known species; in the entire suborder, there are 8,000 described species in more than 800 genera. The wheat stem sawfly has traditionally infested spring wheat, but over the last few decades the damage is becoming increasingly common in winter wheat. Females lay an average of 30-50 eggs, depending on the size of available host stems. Effective December 17, all private dwelling indoor gatherings are limited to immediate households only. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay their eggs. Webmaster | Shallow tillage in the fall has been shown to greatly increase larval mortality. Translations are made available to increase access to Government of Saskatchewan content for populations whose first language is not English. 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