Asparagus beetle activity is on the rise. The adult beetles hide in soil cracks or underneath residue during the heat of the day. Egg laying is often the most obvious sign of their activity. The presence of eggs on the harvest spears, may affect marketability. On young fern, heavy amounts of larval feeding has a negative impact on growth and development.
As harvest concludes, scout plantings regularly as the spears begin to elongate and develop a full canopy of fern. Spray thresholds are as follows:
Eggs: 2 /10 spears with eggs Larvae: 50% of plants with larvae OR 10% Defoliation Adults: 5-10% of plants infested
If controls are required during the harvest season, play close attention to the pre-harvest intervals. Products with a 24-hr pre-harvest interval include: malathion (Malathion 85E), cypermethrin (Mako, Upside 2.5 EC), and acetamiprid (Assail 70WP).
Despite the hot, dry conditions, levels of asparagus rust are increasing in young plantings. Foliar disease management is important in all asparagus plantings. However, fields are particularly susceptible to infections during the first few years of establishment, causing a reduction in productive crown development.
Even in established asparagus fields, rust can have a significant impact on both the spear weight and spear number.
Warm weather with heavy dew, fog, or light rainfall enhances rust development. Infection can occur with as few as 3-9 hours of leaf wetness.
All foliar fungicides are most effective when they are applied before symptoms begin to move into the upper crop canopy. Thorough coverage is essential for good control.
The website, Ontario CropIPM, contains the full range of pest management information from many vegetable crops, including asparagus. Many users do not realize that it is also home to weed galleries, herbicide injury information and critical weed control period information. The following three problem weeds for asparagus are excerpts from the weeds and herbicides section of Ontario CropIPM. Continue scrolling for the best control options for each of the problem weeds. Continue reading Three Problem Weeds for Asparagus→
Young asparagus fields are most susceptible to foliar diseases. Depending on the weather conditions, they will typically appear soon after the plants begin to fern out. Scout regularly, especially as harvest winds down in the immature fields. Both rust and purple spot lesions have been reported in numerous fields this week. Foliar fungicide programs are most effective if they are started at very early stages of development; before the disease gets into the upper canopy, branches and cladophyls. Both diseases start in the bottom 12-24″ of the stem.
Rust (below right) first appears as slightly raised, oval lesions; 2-5mm in length. Depending on the age of the lesion, the colour ranges from pale cream to light green or light orange. Dark orange spores appear as the disease matures. These spores disseminate in the canopy causing further infections.
Stemphylium (below left) appears as a slightly sunken, oval lesion. Very new infections are brownish purple in colour. Older ones have a light tan centre with a darker purple border. Stemphylium spores will also move quickly from the lower lesions into the new growth.
We are interested in scouting immature asparagus fields (2-3 years old) and monitoring the foliar health of these crops over the growing season. If you have a young field, and are interesting in participating in the project, call or email Elaine Roddy (519 674 1616 or email@example.com.
Both rust and purple spot (stemphylium) thrive under cool, wet conditions. Scout fields regularly, at least 2 times per week under high disease pressure conditions. Inspect a minimum of 100 plants per field; looking closely at the bottom 24″ of each stalk. Foliar diseases often first appear in immature and newly planted fields. Continue reading Watch for Diseases in Asparagus→
Determining an ideal harvest duration can be a difficult decision in asparagus. Yield targets are often based on:
the age of the plantation,
number of picks, and
overall spear quality.
2015 has been an interesting year for asparagus. After a long wait, it started with a bang. Many growers reported record yields in the first weeks of picking. Then it slowed down, followed by unusually dry soil conditions.
For the most part, we were expecting good crown health heading into this season. 2014 was cooler and wetter than average, but foliar diseases were well managed and there was a good gradual senescence before freeze up.
We have had reports of asparagus rust in new plantings. Now is the time to get out and scout; especially in the two-year old fields and any volunteer asparagus near the production fields. These plants often act as source of inoculum for the commercial crop later in the season.
Severe rust infections cause the plants to die prematurely in the fall, impacting both the vigour of the crown and the following year’s harvest.
The early infections are slightly raised, light green lesions 10 to 20 mm in length. As they mature, the lesions turn cream-to-light orange (figure 1, asparagus rust aeciospores). Initial infections generally appear at the base of the stalks. Look for these lesions early in the season on volunteer asparagus or two-year old fields. As harvest concludes, scout all fields regularly during the fern development stage. Continue reading Get out and Scout for Asparagus Rust Symptoms→