Rotting Asparagus Plants: Treating Asparagus Crown And Root Rot


By: Amy Grant

Asparagus crown and root rot is one of the most economically disastrous diseases of the crop worldwide. Asparagus crown rot is caused by three species of Fusarium: Fusarium oxysporum f. sp. asparagi, Fusarium proliferatum, and Fusarium moniliforme. All three fungi can invade the roots, but F. oxysporum f. asparagi also invade the xylem tissue, the woody supportive tissue that carries water and nutrients from the roots to the stem and leaves. Learn more about controlling asparagus fusarium crown rot and root rot here.

Symptoms of Asparagus Fusarium Crown Rot

Referred to generally as Fusarium disease, asparagus crown rot, seedling blight, decline disease, or replant problems, crown rot of asparagus results in a decline in productivity and growth, signaled by yellowing, wilting, crown dry rot and eventual death. This soil borne fungus causes infected areas of the crown to turn brown, followed by rotting asparagus plants that rapidly die off.

The stems and cortex are dotted with reddish brown lesions and when cut open, reveal vascular discoloration. The feeder roots will almost completely rot and have the same reddish brown coloring. The rotting, dying asparagus plants infect each other and the disease can spread exponentially.

Management of Asparagus Fusarium Crown and Root Rot

Crown rot of asparagus can survive in soil indefinitely and spreads through movement of infected soil, air currents, and seed contamination. Plant stresses and environmental factors such as poor cultural practices or drainage further open plants up to infection. Positive identification of crown rot is determined through laboratory testing.

Fusarium disease is extremely difficult, if not impossible, to manage once it’s in the field. As the saying goes, “the best offense is a good defense,” so monitor for pests and disease and keep the area around the asparagus crop free of weeds and other plant detritus.

Also, plant disease free seedlings, transplants, or crowns, minimize plant stress, avoid lengthy harvest periods, and be consistent with irrigation and fertilization to lessen the chances that Fusarium will infect the crop.

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10 Most Common Asparagus Diseases and How to Treat Them

Rebekah started a small farm with her husband in 2016 in upstate New York, just north of the pristine Adirondack Mountains, where she grows vegetables and herbs and also raises sheep, chickens, and pigs. There’s nothing she loves more than helping others learn more especially about sustainable living as it pertains to health and homesteading. An avid cook, she works hard to grow and preserve enough food to support her family throughout the year.

I’ve never been very successful at growing asparagus.

The first year I grew asparagus, I completely ignored conventional wisdom (and planting instructions) and harvested asparagus shoots during the first growing season. Rookie mistake! You aren’t supposed to harvest asparagus until at least the second year, and even then it should be done sparingly so that the plants have time to get established.

The next year, I recognized my mistake. I waited and waited and waited to harvest…. and ended up not cutting any asparagus at all because by the point I had built up enough confidence to do so, the shoots were tough and woody.

This year is going to be my year. I felt so confident in my asparagus growing prowess that I even started some plants from seed – and they are doing very well. In preparing for my bumper crop, I did some preventative research about the most common asparagus diseases.

Here’s what you need to know.


10 most common asparagus diseases

1. Purple blot

Purple smear is a disease that usually affects only asparagus plants, unlike many other diseases on this list that target all types of plants.

It is very easy to diagnose. Purple spots will develop on your spear, especially during wet or windy seasons. The good news is that the spots do not affect the taste or texture of your asparagus spears, and they often disappear completely during cooking.

The bad news is, if you are trying to sell your spears or otherwise only see how they look, the purple spots will detach from your overall look.

In addition, if left unclaimed, the spots may develop into complete wounds and grow together in large blobs, eventually killing the affected tissue and protecting the plants.

In most good, moist climates, purple spots can be prevented by following good field hygiene. Cut out last year’s ferns and remove any plants affected by the disease.

2. Rust

Jung is one of the most common asparagus diseases. It presents many symptoms depending on the season.

It first rips its ugly head in spring or early summer, appearing as small, bulging lesions that are usually light green.

Eventually, they change to a whiter or orange color and become more sunken. You may not notice them at first, but as they move, additional wounds will appear around the base of the stems.

Then, a name war develops. This is when the weather warms up in summer. The first set of wounds will burst, spreading spores into the air and infecting other plants. If you brush asparagus ferns and have your hands covered in red paint, you will know that it is for rust.

The problem does not go away as the weather cools, producing black overwintering spores that can weaken the stems the following spring. This can cause the entire plant to die back.

The easiest way to prevent rust is to cut back the fern after it dies in winter. Disposal of infected pieces. Although crop rot is not really possible with asparagus as it is a perennial plant, avoid planting new beds in the same general area as the old ones. You may have to use a fungicide to kill existing spores.

Of course, fungal spores are more likely to infect plants when they are moist with rain or dew. Planting in a location that is sunny and somewhat desolate can help the plants dry up.

3. Fusarium crown rot

Fusarium crown root is usually caused by one of three species of Fusarium fungi: Fusarium oxysporum f. SP. Asparagus, Fusarium proliferatum, And Fusarium moniliform.

This issue, also known simply as Fusarium disease, can cause yellowing, dry rot, wilting and eventually plant death. It is a soil-borne fungus that kills plants quickly after infecting them with reddish-brown sores. This usually causes the roots to rot quickly and die.

Unfortunately, this disease is difficult to prevent and get rid of. Crown rot can remain in the soil for a long time, which is spread by infected air, soil, and seeds.

Plants that are stressed are more likely to become infected, so it is necessary to maintain good cultural practices to avoid stressing their plants. You should also work to improve drainage so that there is no soil.

A simple way to prevent disease is to keep the area around the asparagus free of weeds – these fungi can irritate the spores and make it harder for you to get rid of the disease in the future.

Do not harvest your asparagus plants throughout the season, but rest them periodically so that you do not overstress them. It is also necessary to be consistent with fertilization and irrigation.

4. Frost

Blight, also known as Cracospora Blight, is caused by Sarcospora incompatibility Fungi. It causes brown or tan lesions on small branches of needles and plants with each wound surrounded by a red or brown border. These spores, like other fungal spores, are distributed by wind and rain.

As you might expect, the disease is more common during the wet season period. This can lead to poor photosynthesis and decreased plant yields. Over time, it can reduce the longevity of your plants.

To prevent staining, apply water in the morning so that the leaves have time to dry. Ensure that the plants are spread in rows at a distance of 6-feet so that air can move them between the plants to dry. You may have to get rid of infected plants, but some fungicides can be effective in getting rid of this disease.

5. Dead stem

Dead stem is a fungal plant pathogen that is closely related to the pathogens responsible for common root rot, stalk rot, ear light, and other diseases that can affect other plants such as asparagus and cereal grains.

Another soil borne fungus, the disease can be spread by infected seeds. It is necessary to use sterilized equipment, seeds, and growing supplies. There are many resistant cultivars for dead stems that you can re-grow, ensuring that the soil is healthy and that the disease is also cleared before planting.

6. Phytophthora Crown, Root and Spear Rot

This disease is also fungal, which is caused by the pathogen. Phytophthora asperagii. This is most common when the soil is wet and begins as soft, water-soaked wounds that begin on the plant just above the soil line. Infected plants often turn yellow, and you may find that crowns also die.

Crown, root, and spear rot, left untreated, can dramatically shorten the lifespan of your plants.

The disease is best prevented by avoiding planting in wet areas. You can also apply fungicide to get rid of it.

7. Water Soft Bread

The good news is that this asparagus disease is relatively uncommon. This results from watery-looking sores on your plants that eventually grow to look like white mold. Rigid dark growth may occur in advanced stages of the disease.

The disease is often confused with Fusarium rot – it is only when mold develops that you can actually tell the difference. It often spreads from plant to plant and is more likely to affect plants that have been injured in any way. Avoid harvesting your plants and use sterile equipment when doing so. Again, it is ideal to maintain proper water and soil conditions.

8. Asparagus Mosaic Virus

There are some viral diseases in which asparagus is at risk, but asparagus mosaic virus is one of them. The disease often goes unnoticed with very few visible symptoms. However, it can dramatically reduce your yield and your plants are more likely to suffer from other diseases.

Sometimes the virus will also cause a “mosaic” pattern of light and dark green thinning on the plant.

Removing infected plants can help, as plants can be moved to new locations if the virus is detected in the original planting location. The virus can sometimes be seed-borne, so make sure you are using certified seed stock to start your plants. Pests like aphids can also spread it, so you have to control pests in your garden as well.

This virus can overwinter on your plants to clean the garden after every growing season and keep weeds under control.

9. Zophia Root Rot

Zophia root rot is an asparagus-specific disease that can cause root rot if plants are injured or weakened. It spreads slowly in the rhizome at first, but then moves rapidly to the roots, forming dark caners.

Again, the disease can be difficult to treat and prevent, but following good water and ventilation practices can help keep it at bay.

10. Gray Mold Shoot Blight

Gray mold shoot blight, often referred to as gray mold, is caused by a fungal name Botrytis cinerea. It affects many types of plants other than asparagus, such as strawberries and wine grapes.

The most obvious sign of an infusion is the development of gray mass and rot. It is most common in soils with wet, moist conditions and low pH. Spreading water causes the spores to spread and due to the disease it becomes possible to stay in the soil for a long time.

Avoid closing your asparagus plants together and water them first in the morning so that the plants have time to dry at night. Ventilation and airflow are important in preventing this disease. You should also avoid fertilization with extra nitrogen, as it can increase the incidence of the disease.

Finally, be sure to harvest asparagus every year (after the first year, of course). There is evidence that regular pruning and deliberate removal of bits of plants can help keep the disease at bay. There are some fungicides you can use, too, but many strains of this fungus are resistant, so you have to use them sparingly.


MSU Extension

Mary Hausbeck and Brian Cortright, Michigan State University Extension, Department of Plant Pathology - August 26, 2009

Fusarium and Phytophthora effects on asparagus production

Fusarium species and Phytophthora species can attack and kill asparagus crowns in both nursery and commercial fields. Both of these pathogens can be introduced early in the crown’s life as small infections on either the crown or roots. Over a period of growing seasons and under the right weather conditions, heavy rainfall or drought, these early infections can spread to healthy parts of the crown and start the process of crown death. This process of disease spread on the crown occurs after planting (when the crown is no longer visible) making proper diagnosis of the problem difficult. The deterioration of the crowns can occur unnoticed over several years.

Both cultural and chemical controls have limitations in controlling these pathogens and have been mostly ineffective. Many of the commercial asparagus growing areas have large populations of these pathogens already in the soil. This fact coupled with the long growth cycle of the crop, limits the effectiveness of crop rotation as a disease management tool. Research into tolerant varieties has been limited, and no commercial lines are currently available for planting that show resistance to both pathogens. The practice of planting crowns deep into the soil limits the ability to apply chemical or biological control products at a site where they would be effective. Other factors that can limit the length of productivity of commercial asparagus fields include drought stress, low pH that can favor the devolvement of Fusarium, defoliation of the fern by purple spot and rust, and the use of herbicides that may stress the crown potentially increasing its susceptibility to disease.

A new system of asparagus production needs to be adopted to ensure that newly established fields remain viable and productive to allow for adequate return on establishment investment. This new system will rely on the use of clean crowns grown in properly fumigated fields. Additional measures for crown disease management are also needed to help lengthen field productivity. Crown soaks of effective chemicals will help limit disease on newly planted crowns. Fumigation of production fields will help reclaim fields that have high levels of disease. Controlling foliar pathogens with fungicides will ensure that summer foliage growth has time to recharge the crown for next harvest season. Proper rotation of crops and management of soil pH and soil moisture can help keep crowns vigorous and resistant to infection. Research has been and is currently being conducted on commercial farms to help growers become aware of the benefits of these disease control strategies.

Fumigating crown nurseries

Research from our previous studies has shown that both Telone C35 and metam fumigant products (KPam, Secatagon) are very effective in reducing Fusarium colonies in a commercial field (see Figure 1). The studies also indicated that the highest concentration of disease causing organisms is located in the top 12 inches of the soil profile. Common application equipment is available that can apply both types of fumigants into the top layer of soil where the pathogens populations are the highest. Fumigants need to be applied under favorable environmental conditions (soil temperature and moisture, soil texture, and adequate soil sealing) to ensure they remain in the soil at high enough concentrations to kill the target pathogens. Fall fumigation is preferred as both soil moisture and temperature are more suited for effective applications. Applications in fall also offer more time for field preparation and off gassing needed for crop safety, though minimum soil temperature should remain high enough to ensure effective treatment. Soils that are too cold can limit the amount of fumigant available to kill soilborne pathogens such as Fusarium and Phytophthora.

Figure 1. Colony forming units (CFU) of Fusarium in soil after fimigation

Crown soaks

Even with the best fumigation application, disease levels will be reduced but not eradicated and may result in some diseased crowns used in a production field planting. Additional disease protection can be achieved using a crown soak of effective fungicides. Crowns should be soaked for a minimum of 10 minutes in a registered chemical solution before being planted in the field. Results from the past year’s study shows that the registered product Cannonball has some activity on crown disease and can promote more spear production and taller fern (Table 1).

Table 1. Asparagus crown soak study for Fusarium crown rot. *Column means with a letter in common are not significantly different (Fisher LSD Method P=0.05).

Studies from 2008 (Table 2) shows that other products are also effective in promoting more fern growth compared to untreated crowns. The combination of Topsin M and Presidio had a significant increase in fern height compared to the untreated control. Another combination of Topsin M with Ridomil Gold gave a significant increase in the fern count compared to the untreated control. The combination treatments in this study give a broad range of control for both pathogens. Cannonball and Topsin M will target the Fusarium infections while Ridomil and Presidio will give control of Phytophthora species. Only Cannonball is registered for use as a crown soak and Ridomil Gold is registered as a broadcast application to production fields, but not as a crown soak. Additional studies are needed on the other effective products before additional crop registrations for their labels can be pursued.

Table 2. Asparagus crown soak study from Oceana County, 2008.

*Treatments with the same or no letter are not significantly different (Fisher protected LSD P=0.05).

Planning a cropping system for profitable asparagus

Planting crowns grown in fumigated soil and that have also been soaked in a fungicide solution, are the two most important steps a grower can take to ensure a healthy field establishment. These two steps are the foundation upon which other practices can be built to help prolong the length of a production asparagus field.

Some replant fields may need to be fumigated before planting to reduce the level of disease populations. This type of fumigation will have to cover the entire field and should be viewed as a long term investment with the initial cost being spread over the years the field stays productive.

After the soil pathogens have been reduced via fumigation and crown soaks, each year’s fern growth must be protected from both foliar pathogens and insects that can defoliate the plants. Asparagus miner larva tunnels can also allow the colonization of fern by the soilborne pathogen Fusarium. Long term crop rotation in combination with fumigation can help keep pathogen populations below economic threshold. Maintaining adequate soil moisture with a proper pH level allows the asparagus plant to thrive and resist infection. Herbicide applications and nitrogen sources are other production practices that may have an impact on asparagus health. Preliminary greenhouse studies are being conducted to determine the safety of commonly used herbicides on asparagus growth in both clean and infested soil.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

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Growing asparagus in home gardens

Asparagus (Asparagus officinalis) is one of the earliest harvested vegetables each spring. Asparagus spears are crisp, tender and flavorful. The asparagus harvest season lasts about 6-8 weeks, from early May to late June in Minnesota. In the peak of asparagus season, asparagus spears can grow up to 2 inches per day, producing bountiful harvests for gardeners to enjoy.

How asparagus grows

Asparagus is a unique crop. It is one of the few perennial vegetables grown in Minnesota others include horseradish and rhubarb.

The edible parts of the plant are called the spears. These are technically the stems of the plants. The spears emerge from underground buds at the base of the root system. These buds and roots are called “crowns.” If spears are left to grow, they develop leaves and are called “ferns.” Asparagus harvest is only two months instead of the entire season, because the plants need a chance to let the ferns grow in order to recover and build up energy for the next year.

The fern creates energy that will be stored in the underground portion of the plant to produce the following year’s spears. It is important to take care of the ferns even after the harvest is over to make sure you will have good future harvests.

Soil pH and fertility for asparagus

Soil testing and fertilizer

Asparagus grows best in well-drained soils with a pH between 6.5 to 7.0 and does not tolerate extremely acidic soils. It can grow in heavy, medium, or sandy soils, as long as the soils must be well-drained and do not exhibit pooling water after rains.

Before planting asparagus, have your soil tested to see if the soil has the right amount of nutrients for asparagus to thrive. Add recommended fertilizer based on the soil test results. It is best to add part of the fertilizer the fall or spring before planting, but about half of the phosphorus and potassium should be added at the time of planting. Nitrogen should be added after planting, once the crowns begin growing.

In the absence of a soil test report, the typical garden fertilizer rate for asparagus is to apply 1 to 1.5 pounds of a 10% nitrogen, 10% phosphorus, and 10% potassium fertilizer (10-10-10) per 100 square feet before planting.

Once an asparagus patch is established, it is best to test the soil approximately every three years and follow the test recommendations before adding nutrients. After the asparagus patch is established, fertilizer, compost, or composted manure can be added either in early spring before spear emergence, or after harvest in late June or early July. Only add these inputs if they are needed according to the soil test. Add the fertilizer alongside the row of plants and scratch it in lightly. Do not allow the tool to penetrate the soil more than an inch deep, to avoid harming the underground portions of the plants.

If your soil test shows that the garden is high in phosphorus, use a low phosphorus fertilizer such as 32-3-10, 27-3-3, or 25-3-12, or use a non-phosphorus fertilizer such as 30-0-10 or 24-0-15 at the rate of ½ pound per 100 square feet. Avoid adding unnecessary amounts of phosphorus to the soil beyond what the soil tests recommend. Continuous use of high phosphorus fertilizer such as 10-10-10 or 15-30-15, or high rates of manure or compost can result in phosphorus buildup in the soil that impacts soil and plant health over time.

Do not use any fertilizer containing an herbicide (i.e. a "Weed and Feed"-type product), as it may kill your vegetable plants.

Selecting plants

  • There are female plants and male plants. This means the plants are dioecious.
  • All produce edible spears.
    • Only plants with all female flowers produce red, inedible berries in summer.
    • Female plants grow larger spears.
    • Male plants grow a greater number of smaller, uniform spears.
  • Most hybrids, such as Jersey Giant, are plants with only male flowers that produce no seeds.
    • Plants with all male flowers do not use energy on developing seeds and fruits.
    • Male asparagus plants tend to live longer and produce more spears.
  • Female plants can produce undesirable weedy seedling asparagus plants.

Varieties that do well in Minnesota

Varieties recommended for Minnesota include:

  • Millennium: A newer variety from the University of Guelph. It is very vigorous and high yielding.
  • The Jersey” series: Jersey Giant, Jersey Knight, Jersey Supreme. The Jersey varieties are popular and very high yielding. These varieties can be damaged at -30° F if there is not enough snow cover.
  • The Washington” series: Mary Washington and Martha Washington. These are open-pollinated varieties. Yields are lower than the Jersey varieties, but they are very cold hardy.
  • Viking KB-3: An open-pollinated variety
  • Purple Passion: A purple, open-pollinated variety

Planting

A planting of asparagus can last 15 years or more, so choose the spot for an asparagus bed carefully.

Choose a fertile, sunny, well-drained site with soil that holds moisture well.

Late spring frosts can kill emerged spears, so find an area that is not low-lying or exposed to frost.

Asparagus plants have deep root systems. Avoid areas with shallow soils, or soils prone to water-saturation.

If the asparagus bed is to be part of a larger vegetable garden, the best place is at the north end of the garden, so that the tall ferns do not shade the other crops.

Following correct planting methods for asparagus is important for this long-lived perennial crop.

In Minnesota, asparagus is planted between early May and early June. When ordering crowns online, select a delivery date close to when you hope to plant, and refrigerate the crowns until planting.

Prepare the planting area as described above. Then, dig a 6-12 inch deep furrow (trench) for the crowns to be planted into. In heavy clay soils, make the furrows more shallow (6-8 inches) and deeper (10-12 inches) for very sandy soil. As the soil is removed from the trench, set it directly to the side. It will be returned to the trench several weeks later as the ferns grow.

The length of the trench should be as long as the number of crowns being planted. For example, if you have 10 crowns, dig a 10-foot long trench. If planting multiple rows, space the furrows at least 3 feet apart, because the plants will spread as they age.

To plant the crowns, place them "head-to-toe" (bud-to-root tip) in a line down the furrow, so that the buds of the crowns are spaced above 12 inches apart. See the photo below:

Some very old publications and online gardening blogs may say to spread out the roots of the crowns like an octopus during planting, but this is an outdated, unnecessary practice.

Adding a fertilizer containing phosphorus and potassium to the furrows at the time of planting will help make sure the plants can access adequate nutrients as they grow.

Next, cover the crowns with 2-3 inches of the soil that was removed from the furrow previously. The rest of the remaining soil will be added to the trench a few weeks later, once the ferns have emerged and grown. Do not let the crowns dry out between placing them in the furrows and covering them with soil. Water immediately after planting.

After planting, there should still be plenty of soil along the sides of the furrows, which will be used later in the season to continue back-filling the furrows as the ferns grow.

Small, narrow spears will start to emerge from the soil within 2-3 weeks of planting, depending on precipitation, temperature and amount of soil cover. Once the spears are sturdy and several inches tall, several more inches of soil can be back-filled into the furrow. Use caution with this step, as large clods of dry soil can break the brittle spears.

Asparagus is typically planted as crowns, rather than seeds. However, gardeners wishing to try starting asparagus from seed may follow these recommendations:

Choose an area of the garden as a nursery bed. Young asparagus plants will grow here for their first year. The site for the asparagus nursery should be level and have sandy soil.

Plant seed in spring, about one inch deep, spaced two to three inches apart, within rows that are a foot apart. Seeds can take three weeks to germinate.

Keep the nursery bed free from weeds, as the asparagus seedlings will not be able to compete with strong weed growth.

Mulch the nursery bed with four to six inches of straw in late October to keep it warm during winter.

In early April, before the plants start to grow, dig up the crowns with as much of the root system as you can, and move them to their permanent location, following the method described below for planting crowns.

How to keep asparagus healthy and productive

Soil moisture is important for good root and fern growth in asparagus. Even though asparagus ferns rarely exhibit obvious signs of drought stress, they need consistent soil moisture in order to stay healthy for the next year. Watering during the harvest season may also increase yields in very dry years.

Asparagus patches should receive at least one inch of water every week. If they have not received an inch of rain in the last week, soak the soil with water. Asparagus growing in sandy soil should be watered more than once per week in the absence of rain, and heavy clay soils may not need to be watered as often. Additionally, soils covered in mulch will retain more water.

An inch of water will wet a sandy soil to a depth of ten inches, and wet a heavy clay soil to six inches.

Weeds compete with asparagus for soil nutrients, water, and light, so managing weeds will help support a more bountiful yield of spears. Removing weeds by hand is still one of the most effective methods, especially in smaller asparagus beds. Additional methods include well-timed hoeing, flame-weeding, cover crops, and careful use of select herbicides.

Perennial weeds like Canada thistle and quack grass thrive in asparagus because it is a perennial crop that is rarely cultivated or tilled.

In larger asparagus gardens with multiple rows, managing weeds between the rows is relatively easy compared to managing weeds in the asparagus rows themselves.

Non-chemical weed management

Cultivation (hoeing and tilling): Cultivation is an effective weed management tool for vegetable gardens in general, but be cautious when using it in asparagus. Cultivating too deep, or at the wrong time in the season, can damage the crowns and emerging spears.

There are two times when asparagus beds can be cultivated: Before the spears come up in the spring, and after all of the spears are harvested but before ferns come up in late June. At both times, the cultivation must be very shallow, less than 2 inches deep.

Cultivating in the spring allows for the addition of fertilizer to the soil, but can also stimulate the growth of weed seeds that were previously buried. Therefore, gardeners should only cultivate in the spring if it is truly necessary for removing the weeds in their patch, and if they need to add fertilizer.

Do not cultivate the asparagus rows during the harvest season, when new spears are coming up every day. In larger patches with multiple asparagus rows, cultivation can be used at any time between the rows.

Cultivation is most effective on small, young weed seedlings and is not likely to control perennial weeds or large, established annual weeds.

Cover crops: In larger patches, perennial cover crops (groundcover plants) can be planted between asparagus rows. Healthy, dense cover crops can help outcompete weeds, without disturbing the soil through cultivation. Use a perennial cover crop mix including species like fescues, perennial ryegrass, and clover that are hardy in Minnesota.

Flaming (propane weeding): Flame weeders, also called propane weeders, emit heat and flames from propane-powered torches. Despite the name “flame weeder” this tool is not meant to burn the weeds. Instead, it is meant to kill the weeds by heating them to high temperatures. Small scale flame weeds for home gardens are available.

Hand-removal: In small asparagus patches such as home gardens, hand weeding can actually be one of the most effective and efficient ways to remove weeds. Hand removal is necessary to manage large annual weeds and perennial weeds. Hand removal is also the safest way to keep weeds out of the rows during the harvest season (May-June). Hand-removal can also be used to eliminate any weeds that escape through cover crops and mulches.

Hand-removal is the most efficient way to eliminate stubborn perennial weeds like Canada thistles and quackgrass in asparagus. Flaming and mowing are not effective tools for managing Canada thistles in asparagus, because the plants will continue to reproduce even if the tops are removed or burned.

Mulching: Straw and leaves can be used for mulch in asparagus beds to help smother weeds. However, these mulches also keep the soil cooler and wetter, potentially delaying or reducing asparagus spear emergence in the spring. Therefore, push the mulch away from the rows in the early spring to allow the soil to warm and encourage spear growth. In larger patches with multiple rows, the aisles between the rows can be mulched using wood chips, straw, or landscape fabric.

New Crown Plantings

Good weed management is critical for establishing high yielding, healthy new asparagus beds. As described previously, most new asparagus patches are established by planting one-year-old crowns into deep furrows. The newly planted crowns have very small root systems, so just a few weeds around each plant can cause the plants to grow slowly and produce fewer spears later on.

Using herbicides in garden-scale asparagus patches


Prevention of Asparagus Diseases

If you understand a few things about these fungal diseases it will help you decide what preventative measures to take:

Even if you are starting an asparagus bed in a previously unused location away from other asparagus the fungi can be introduced from diseased crowns. You can try dipping your asparagus crowns in a fungicide solution before planting. Equally seeds can be surface contaminated with spores. An Asparagus Information Bulletin (no 202) issued by the Cooperative Extension at Cornell University suggest disinfecting seed for 2 minutes in a solution of 1 part commercial 5.25% sodium hypochlorite to 4 parts water, rinsing, drying and planting immediately unless pre-soaking is planned.

The spores live over the winter on plant debris so always cut back the ferns as they die back for the winter, remove them from your vegetable patch and burn them. Take a look at our page on

Aspargus Care if you are not familiar with this process.

Spores may also overwinter in the soil. Try not to plant a new bed in the same place as an old one or the spores that took a while to build up in your old bed as it matured will be waiting to spring into action on your new bed whilst it is still young.

The spores infect plants more easily when the plants are damp either as a result of dew or rain. Try to chose a spot for your plants that it not only sunny but has a breeze running through it to keep your plants from being overly damp.

If you know there are other asparagus beds around or you are planting over an old bed (because you have no choice) chose one of the more resistant varieties. Take a look at our Asparagus Varieties Page for information on the disease resistance of different varieties of asparagus plant.

Fungi thrive in the damp and asparagus beds that hold too much moisture may lead to the "rots" setting in. If you have planted your bed on heavy soil which is holding a lot of moisture you could well get this problem.

Generally plants that have rust are more susceptible to other asparagus diseases so treat your plants well for rust to help prevent rot!

On top of that if your plants are infested with asparagus beetle they will also be more susceptible to rust and rot. For more information on the Beetles that infest Asparagus plants follow this link .


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