Strawberry and Raspberry Pest Management in Wisconsin

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Leaf diseases
caused by fungi
particularly susceptible following one or more nights of irrigation for
frost control. Use copper sprays as soon as possible afterwards to
prevent crop loss. Note, though, that copper can cause leaf yellowing.
Discontinue copper treatment if you observe plant damage.
Leaf spot, leaf scorch, and leaf blight are caused by distinct fungi, and
each disease has distinct symptoms. Management recommendations,
however, are similar for these diseases. If they are frequently a problem
in your area, select resistant cultivars (table 5). Remove leaf debris from
the site following renovation to reduce inoculum for the following
year. Several fungicides are available for controlling leaf diseases; read
the label carefully since application times vary.
Soilborne diseases The pathogens that cause black root rot, red stele, leather rot, and
Verticillium wilt are active in the soil and affect the functioning of roots
and crowns. The most common symptom associated with leather rot,
however, is off-color, bitter, leathery fruit; infection occurs when fruit
touch the soil or spores splash onto fruit. Soilborne diseases can be
managed by combining cultivar resistance (table 5) and sound cultural
practices; planting on well-drained sites is critical. If red stele is severe,
early spring and postharvest application of Ridomil to the root zone, or
foliar application of Aliette, or a phosphorous acid product, is
recommended (see table 6).
Gray mold
(Botrytis fruit rot)
Botrytis cinerea is a common fungus on many plants and can infect
strawberry flowers and fruits, especially during cool, wet periods. The
cultivars Honeoye, Raritan, Tribute, and Tristar are relatively tolerant;
Glooscap and Kent are susceptible. Elevate, Pristine, and Switch are all
very effective against gray mold. Good coverage during bloom is
essential; if primary infection is prevented, later sprays may not be
necessary. Therefore, one spray should be made during early bloom
when about 5–10% of flowers open (25–50% of king or primary flowers
open) and a second made during full bloom. Since different cultivars
vary in timing of bloom, treat cultivars separately. B. cinerea is prone to
become fungicide resistant, so alternate or combine fungicides to
prevent the selection of resistant pathogens (see Fungicide Update).
Anthracnose fruit rot Anthracnose fruit rot, caused by various forms of the fungus
Colletotrichum, is becoming increasingly important in the United States,
and severe outbreaks have occurred in Wisconsin. Symptoms are soft,
tan to brown, sunken water-soaked spots on green or ripe fruit. Under
humid conditions, slimy pink spore masses sometimes develop on
lesions. The disease is favored by warm and humid or rainy weather. If
anthracnose was a problem in a planting the previous year, fungicides
should be used before symptoms appear, or immediately upon
detection if the planting is being regularly and thoroughly scouted.
Abound, Cabrio, Pristine, or a mixture of Topsin-M and captan at the
high end of rates permitted on the label are the most effective
treatments (see table 6). However, control with fungicides has not been
consistent, and fungicides will not save a crop after symptoms are
widespread.