Fire Blight of Apple. Fire blight is a serious threat to apple production
in Illinois. It occurs every year, causing blossom blight, shoot blight canker
blight, and rootstock blight on apples and pears. To control fire blight of
apple, dormant copper spray and application of antibiotic during bloom is
essential. Copper must be sprayed prior to or at silver tip growth state.
Copper should be applied to the entire orchard block, including non-susceptible
cultivars. The reason for treating non-susceptible cultivars is that even
normally fire blight resistant trees can be colonized by the bacteria and
serve as a source of infection during bloom. Several copper compounds can
be used in the dormant sprays. If copper sulfate is used, it must be applied
when trees are dormant. If copper sulfate is applied later than silver tip,
plant injury can result. Also, do not apply copper sulfate with oil;
apply copper sulfate and dormant oil as separate sprays spaced at least 10
days apart. Fixed coppers such as Kocide and C-O-C-S can be tank mixed with
early season oil sprays. For more information, consult the “Illinois Commercial
Tree Fruit Spray Guide 2004.” Also, a detail information on fire blight can
be found at the website: http://www.aces.uiuc.edu/vista/abstracts/a801.html
and http://www.caf.wvu.edu/kearneysville/disease_descriptions/omblight.html.
Apple Scab. Early
season spray for control of apple scab is essential. The first spray must be
applies at green tip. Primary scab spores are mature and disseminated at early
bloom. There are several fungicides (i.e., Nova, Sovran, Flint, Topsin-M,
captan,…) that effectively control apple scab. For more information on control
of apple scab, consult Illinois Commercial Tree Fruit Spray Guide 2004.a Also, more
information on apple scab is available at websites:
http://www.aces.uiuc.edu/vista/abstracts/a803.html,
http://www.ipm.ucdavis.edu/PMG/r4100411.html,
and http://extension.usu.edu/plantpath/fruit_diseases/fd_apple_scab.htm.
Brambles Anthracnose. To control anthracnose on brambles, a delay dormant spray is needed.
This is a critical spray. Liquid lime-sulfur (20 gallons per acre), or copper
hydroxide (Blueshield 50WP or Kocide 50WP) at the rate of 4 lb per acre, should
be applies when new shoots are ¼ to ¾ inches long. The spray may burn the
leaves if applied after new shoots are ¾-inch long. For more information,
consult the AMidwest Commercial Small Fruit and Grape Spray Guide 2004.a Also, detailed
information on anthracnose of brambles can be found at the website:
http://www.aces.uiuc.edu/vista/abstracts/a700.html.
New Fungicides for Fruit Crops. Four new
fungicides (Agrifos, Endura, Phostrol, and Pristine) have been labeled for use
on fruit crops. Label information is available in the following website:
Phostrol: http://www.cdms.net/ldat/ld4HL003.pdf.
Endura: http://www.cdms.net/ldat/ld6CU002.pdf.
Pristine: http://www.cdms.net/ldat/ld6DD003.pdf.