Northern Michigan FruitNet 2009
Weekly Update
NW Michigan Horticultural Research Station
| Nikki Rothwell District Horticulturist |
Erin Lizotte District Fruit IPM/IFP Agent |
Bill Klein Farm Mgr, NWMHRS |
| Duke Elsner Agricultural & Regional Viticulture Agent |
May 26, 2009
GROWING DEGREE DAY ACCUMULATIONS AS OF May 25th AT THE NWMHRS
Year |
2009 |
2008 |
2007 |
2006 |
2005 |
2004 |
19yr. Avg. |
GDD42 |
516 |
454 |
625 |
628 |
543 |
466 |
518 |
GDD50 |
245 | 203 | 312 | 300 | 253 | 205 | 250 |
Growth Stages at NWMHRS (5/25/09- 12:00
p.m.)
Apple: McIntosh – Petal fall
Yellow Delicious – Early petal
fall
Gala – Early petal fall
Red Delicious – Early petal fall
Pear:
Sweet Cherry: Hedelfingen: 11 mm fruit
Napoleon: 7 mm fruit
Gold: 8 mm fruit
Tart Cherry: Early shuck split
Balaton: In the shuck
Apricot: 12 mm fruit
Grapes: 1-3” shoots
Weather
We finally had some warm
weather over the past week but the dry conditions have continued. Rain is in the forecast through
Thursday. Last Thursday, the region
received some scattered showers with most regional stations reporting no more
than 1/10” rain, the ground is still dry. We have accumulated 516 GDD base 42
and 245 base 50. We are almost equal to the 19-year average, which is 518 GDD
base 42 and 250 GDD base 50.
Crop Report
Tree fruit
Pears are at 6mm, apricots
are at 12mm and plums are at late petal fall. Apples are at petal fall.
Montmorency and Balatons® are at early shuck and
sweet cherries are at 7-11mm at the Northwest Station. We have seen tremendous bloom and great
pollination weather in apple this year, which may make thinning a challenge.
In apples, spotted tentiform leafminer numbers
are back up at the station with catches averaging 50 adults per trap, compared
with 10 per trap last week. Eastern tent
caterpillar webbing is visible throughout the region at higher levels than
commonly seen. Under high pressure, Eastern tent caterpillar can be a pest in
apple and cherry and may require control this season. We continue to catch plum curculio in low numbers around the
region. The first codling moth catch was reported out of
As we move through the week,
rain is again in the forecast and based on a biofix of April 25 (McIntosh green tip), apple tissue should be kept covered with ascospores maturing approaching 100% and discharge forecast
at 77% percent spore over the next week. A light-moderate apple scab infection period was predicted in some areas last
Thursday and we will expect to see symptoms on June 3. With the small amount of rain on Thursday, we
also saw a fire blight infection
period predicted with EIP values well over 100. Many area growers applied their first streptomycin application of the
season. If temperatures on your farm
are different from the weather station reading, be sure to try out the new Fire Blight Interactive Predictor Model at www.enviroweather.msu.edu.
The interactive model allows
you to input your own data and determine the risk of fire blight for your
individual farm.
In cherries, we are hearing reports and
observing very high levels of green
fruit worm with a lot of larvae feeding on foliage. We continue to catch American plum borer this week (37 moths
per trap). Growers with infested blocks
should be managing for this pest around petal fall in conjunction with adult
flight in their blocks. We continue to catch plum curculio around the region. Growers should keep an eye on the cherry
leaf spot infection model. Remember, leaves must be unfolded, exposing the
stomata for leaf spot infections to occur.
Small fruit
For grapes, we have yet to catch potato
leafhopper or grape berry moth in trap lines around the region. Climbing cutworm damage has been reported from one area vineyard, and we continue to see a few grape leafhoppers on sticky traps.
For an updated version of
the pest report during the week, call (231) 947-3063.
CONSIDER
NEMATODES WHEN ESTABLISHING ORCHARDS AND VINEYARDS
Diagnostic Services
Many things need to be considered when establishing or
replanting an orchard or vineyard, but the impact of plant-parasitic nematodes
should not be ignored. Feeding by many species of nematodes will produce
unthrifty trees and subsequent yield reductions. Unfortunately, often the cause
of these symptoms is undetermined. Since all species of plant-parasitic
nematodes are microscopic, the only way to diagnose nematode problems is to
collect soil and root samples and to submit them to a nematode diagnostic lab
for analyses. It is highly recommended new orchard or vineyard sites are
sampled for nematodes before their establishment. Although this article focuses
on pome fruits, stone fruits and grapes, the same is true for plantings of
brambles, blueberries, strawberries and any other fruit.
The recent withdrawal of fenamiphos (Nemacur) as a post-plant nematicidal option on pome, stone and small fruit magnifies the importance of sampling
prior to planting. In the past, if nematodes were abundant on a site at
planting but went undetected or nematode-infested planting stock was purchased
or used, Nemacur could be used as a rescue treatment
and would provide adequate to excellent control of these pathogens. However,
with the withdrawal of Nemacur, there are no
post-plant chemical options for nematode control in bearing orchards, grapes or
small fruit plantings, so most management strategies and tactics must be
implemented prior to orchard or vineyard establishment.
If old orchards or vineyards are too be removed and replanted, growers should
make observations prior to these events. Are some of the trees stunted and what
are the possible causes? Do any of the symptoms appear to be caused by viruses?
If the answer to either of these questions is “yes,” nematodes may be
implicated as causal agents or vectors. Proper identification of viruses is
very important. Dagger and needle nematodes are common parasites of fruit and
are notorious vectors of certain plant viruses. Where they are pathogens (cause
disease), dagger nematodes, in particular, aren’t extremely virulent (amount of
disease). However, only one dagger nematode is necessary to transport viruses
from one tree to another. Therefore, if old orchards or vineyards are infected
with nepoviruses (nematode-transmitted polyhedral
viruses), dagger and needle nematode control is vital before establishing new
plantings. Many broadleafed weeds are also
symptomless carriers of some nepoviruses, so
observations about weed pressure are also important.
Typically, after removal of an old orchard or vineyard, some remediation of the
site will occur before replanting. This is typically done by growing cover or
rotational crops or even allowing sites to sit idle. These periods represent
good windows for nematode control. However, it is virtually impossible to
develop a sound rotational scheme or to choose the proper cover crops if the
types of plant-parasitic nematodes present are not determined. For example,
rape, cv. Dwarf Essex, is a great choice if dagger nematodes are present on a
site, but it may not be real effective against lesion and northern root-knot
nematodes. Pearl millet should be very effective against lesion nematodes but
possibly poor against dagger nematodes. Therefore, the collection of soil and
root samples is necessary for identification and enumeration of important
nematodes present in any given location in order to design rotational schemes
to reduce their population densities.
Maintaining good soil health is very important for proper nutrition and growth
of plants. With orchards and vineyards, it is very critical to check soil pH
deep in the soil prior to establishment because, on occasion, soils in the
rooting zones of trees and vines are very acidic. At low pHs,
heavy metals are much more mobile and in concert with other causal agents, such
as nematodes, growth can be significantly reduced. In these types of
situations, young trees may even die.
All your diligent work to avoid nematode problems prior to planting can be
wasted if nematode-infested planting stock is used. Virus certification
programs often work well to reduce or eliminate the sale of trees or plants
infected with viruses, but nematodes often go unchecked. If sites are fumigated
prior to planting nematode-infested stock, severe problems may result as
nematode population densities can increase dramatically if unchecked by biocontrol agents or competing organisms.
Management of plant-parasitic nematode populations requires an integrated
approach. However, it all begins with a sampling program. Once nematodes are
properly identified informed decisions can be made regarding fumigation, cover
crops, resistant rootstocks, etc. In
Insect and disease predictive information is available at:
http://www.enviroweather.msu.edu/home.asp
http://www.agweather.geo.msu.edu/agwx/forecasts/fcst.asp?fileid=fous46ktvc
http://www.cherries.msu.edu/
Fruit CAT Alert Reports
http://www.ipmnews.msu.edu/fruit/
This issue and past issues of the weekly FruitNet report are posted on our website at: http://www.maes.msu.edu/nwmihort/faxnet.htm
ACTUAL
AND PREDICTED DEGREE-DAY
ACCUMULATIONS
SINCE MARCH 1, 2009
Please send any comments or suggestions regarding this site
to:
Bill Klein, kleinw@msu.edu
Last Revised: 5-26-09
