Category Archives: Asparagus

Time to Scout for Asparagus Beetles

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).

Spotted Asparagus Beetle (Hannah Stevens, retired MSU)
Common asparagus beetle (Hannah Stevens, retired MSU)

Scout for Asparagus Rust

Asparagus Rust (uredospores)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.

Rust yeild loss

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.

 

 

Three Problem Weeds for Asparagus

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

Rust and Purple Spot Appearing in Young Asparagus Fields

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 elaine.roddy@ontario.ca.

 

Watch for Diseases in Asparagus

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

Difficult Decisions for Asparagus Harvest

Determining an ideal harvest duration can be a difficult decision in asparagus. Yield targets are often based on:

  • the age of the plantation,
  • tonnage,
  • calendar date,
  • market price,
  • 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.

That being said, over the past few weeks there has been a noticeable decline in spear quality, with a high proportion of pencil-thin whips in the fields. Understandably, growers are concerned and looking for possible causes. Continue reading Difficult Decisions for Asparagus Harvest