DISEASES
DISEASES & PESTS
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Crown rot and root rot
- Asparagus is affected by two Fusarium species.
- The first is Fusarium oxysporum pv. asparagi which causes crown rot; and the second one is Fusarium moniliforme which causes root rot.
- The crown rot fungus is found in most soils but at very low levels.
- If asparagus crowns are planted that have crown rot they will not produce spears for more than 4 to 7 years, and this is not profitable.
Control measures
- Do not plant asparagus in soil in which asparagus has been grown in the last 5 years.
- Do not purchase crowns grown in soil where asparagus was grown in the last 5 years.
- Purchase only certified crowns, keep asparagus growing rapidly to reduce crown rot disease by following the recommended management practices.
- The root rot pathogen may be spread through asparagus seed. Make sure to treat seeds for producing crown.
Cercospora blight : (Cercospora asparagi)
- Symptoms include small, oval and grey to tan lesions (spots) with reddish brown borders on the needles and small branches.
- It causes the needles to fall from the mature fern.
- It can be identified by the browning of needles.
- The disease occurs when the humidity and temperature are very high.
Control measures
- An integrated approach of several cultural practices will help provide partial control.
- Schedule overhead irrigations to allow thorough drying of the foliage before nightfall, or use drip or furrow irrigation to keep foliage dry.
- Wider row spacing will increase the air movement to dry foliage and delay canopy closure.
- Rows should also be planted in a north-south direction to take advantage of prevailing southerly winds in drying foliage burning.
- Disposal of infested residue in the spring delays blight appearance by about one week.
- There are no known asparagus varieties resistant to Cercospora blight.
Soft rot: ( Erwinia spp.)
- Harvested asparagus is susceptible to bacterial soft rot.
Control measures
- Management is based on avoiding injuries and immediately cooling harvested spears.
- Wash water and water used for hydrocooling should contain chlorine.
Rust : ( Puccinia asparagi)
- It is not a common disease.
- Rust causes small brown rusty pustules on spears and fern branches.
Control measures
- Asparagus beetles and their larvae attack on spears and ferns.
Control measures
- Spray carbaryl (0.1%) to control this insect.
Army worms
- Army worms can be especially bad on young ferns.
Control measures
- These can be controlled by deltamethrin (0.0025%) or carbaryl (0.1%).
- It can be a problem occasionally.
- The blue-green aphid forms colonies in August or September.
- When the aphid forms colonies, it causes "Christmas tree" or bonsai effect.
- The new fern becomes shortened or stunted and new needles look like they are clustered.
- The entire plant takes on a blue green colour.
Control measures
- It can be controlled with a spray of malathion (0.05 %) or oxy-demeton methyl (0.025 %).
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Last modified: Sunday, 17 June 2012, 5:39 AM