Answer: You probably depleted your asparagus crop's reserves by harvesting too many spears last year, thus causing thin spears to grow this season, explains Steve Garrison, Extension vegetable specialist at the Rutgers Horticultural Research Center in Bridgeton, New Jersey. For healthy crowns and ferns, stop harvesting spears by June 15th. If the crowns appear weak and the ferns small, stop cutting spears by June 1st. This should give the crowns enough time to replenish their reserves for the next spring, he says. Another possibility for lack of spears is aphid damage. Severe aphid infestations cause spears to quickly grow into ferns, Garrison explains. By stunting growth one year, aphids affect the next year's spear production. Signs of aphid damage are smaller than normal ferns with a rosette appearance, he says. To control them, spray aphids weekly with insecticidal soap or release predator insects such as ladybugs.
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