SW Michigan Fruit Update
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Southwest Michigan, April 27, 2009
Weather
The weather the last two weeks has been a rollercoaster with highs ranging from 50 to 80 and lows ranging from 26 to the mid 50s. Two weeks ago rain on April 13-14 and brought a third to a quarter inch of rain. Then temperatures rose to 70 and lows around 50 causing rapid growth and bloom began in early blooming stone fruits. Sunday, April 19, brought a large-scale rain event that lasted three days and left about an inch of rain. This rain was a wide spread scab infection event. As the storm passed the weather cleared and we had a radiation freeze on the morning of April 23. This freeze dropped temperatures into upper twenties and caused freeze injury to most crops. Very warm conditions returned after the freeze with highs above 80. The warm weather was accompanied by thunderstorms that caused another wide spread infection event for many fruit diseases on April 25. The passage of another front Monday was accompanied by strong rain and another infection event Monday night.
The forecast is for another front to pass Thursday and for cooler and wetter than normal weather for the next week or two. I expect slower crop development with cooler wetter weather this week.
Southwest
Michigan Growing Degree Day Totals
|
Grapes, from April 1 |
|||
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
272 |
204 |
122 |
82 |
|
226 |
167 |
96 |
70 |
|
You can find weather and IPM information for Southwest Michigan at the Enviroweather website. Here is a link a table of SW Michigan’s Growing Degree-Days from March 1 to April 26, 2009. After the last weeks heat 2009 is close to earlier years back to 2004, here is a comparison of Growing Degree Days to April 26 in past years. There are also maps showing the current Degree-day accumulations for the state and the departure from the long term average. Please note from the caption on the maps that they use
Tree fruit
Bloom is underway in stone fruit and growers need to protect against blossom brown rot in apricots, peaches, sweet cherries and Japanese plums. This disease requires wet and warm conditions, and only 5 to 6 hours of wetness at 70F. .
Apricots bloom began about a week ago and bloom is ending. Since the few apricots we have are in sites with good air drainage, little damage was caused by the freeze last Thursday April 22.
Peaches are blooming. Bloom appears to be heavy and there appears to be little damage to peaches from the cold temperatures in mid January. Additionally, peaches seem to have suffered little damage from the recent freeze. Copper sprays can be used to reduce bacterial spot by reducing the bacterial population. No more than 1 pounds of metallic copper should be used at this time. Symptoms of peach leaf curl should not appear for several weeks when leaves have fully emerged. Oriental fruit moth traps should be out to monitor emergence of this pest. If you are planning on using mating disruption on the first generation of Oriental fruit moth you need to get your pheromones out soon.
Sweet cherries are at full bloom and leaves have emerged. Sweet cherry blossoms and fruit are always susceptible to brown rot. Because the leaves are out growers also need to protect against cherry leaf spot. Poor development of fruit buds in sweet cherry is the result of winter injury to the flower buds. Growers should be aware of black cherry aphid, scout for curling of the new leaves.
Tart cherries are just beginning to bloom. Brown rot infection of the flowers in tart cherry is a rare event needing good warm rain, which is unlikely in the next week. When leaves emerge and unfold then you will need to apple controls for cherry leaf spot. ‘Balaton’ cherries are also at first bloom. There are reports of scattered light damage (~10%) from the freeze last Thursday.
In Plums, European plums are blooming. Oriental plums are at petal fall. Growers will need to apply protectants to reduce black knot as shoot growth begins.
Apples are at pink to open cluster. Bloom has begun with IdaRed and Zestar. There have been many widespread apple scab infection events this spring and scab spores are caught in good numbers during the rains. Growers should apply apple scab fungicides during pink just before bloom to assure complete coverage of the developing flower, before the petals open. Symptoms from recent scab infections should show up about May 5. Wet weather during bloom risks fire blight infections. There will be a new model for fireblight available on the enviroweather website soon allowing growers to more easily track the disease. The cool conditions forecast for the next few days will suppress the growth of the bacteria and lower the risk of the disease. If the average daily temperatures remain below 60F, there is little risk from the disease. A section 18 was granted for Kasumin (Kasugamyacin, see MSU Fruit CAT Alert article) but it is unlike that any materials will reach Michigan this week; fortunately the cool weather makes infection unlikely. Fire blight infections are more likely to develop later in bloom when warm rains occur. There is little insect activity to report. Spotted tentiform leafminer adults are flying. Grower and scouts should place insect traps for Oriental fruit moth to monitor biofix in their orchards.
Pears are blooming. Pear scab is a concern as there is green tissue out and the infection conditions are similar to apple scab. Pear growers can use the apple scab model at the enviroweather site to track pear scab. Pear Psylla eggs and nymphs are hard to find.
Small
fruit
Blueberry fruit buds are bursting and leaf buds are
unfolding. Many blueberry fields are flooded from the recent rains. I have
noticed winter injury of fruit buds in ‘Bluecrop’ where the fruit buds show
little if any growth (picture on left). Other major varieties show little
injury. This injury is distinctly different from bud death due to the infection of
the bud by phomopsis (picture on right). Many of the cold injured buds show green
growth, where phomopsis killed buds are black and the supporting tissue on the stem is
black also. Growers with phomopsis and not winter injury will want to focus
fungicide applications on phomopsis affected fields. Mummyberry
mushrooms are out and recent rains were mummyberry infection events.
The Michigan Blueberry IPM Newsletter is posted at the MSU Blueberry
IPM Update Newsletter. The first Blueberry IPM Update meeting is planned for May
13 at the Bodtke Farm at 01240 57th Street, west of Grand Junction MI.
Grape buds are at first swell to bud burst. At this stage the buds are susceptible to cutworms, which seem to like cool damp weather. See the most recent copy of Grape IPM Newsletter at the MSU Grape current conditions webpage. Here is a link a table of SW Michigan’s Growing Degree-Days from April 1 to April 19, 2009.
In Strawberries, new leaves are emerging and flower trusses are still in the crown. I expect that the flower trusses will begin to emerge this weekend. Bloom has started in extreme southern Berrien County.
Raspberries are leaves are out and under these wet conditions fungicides to protect green folage crucial to protect against foliage diseases.
Cranberries are dormant.
Miscellaneous
Growers are pruning and clearing brush.
The Fruit Code-A-Phones in Van Buren County (269) 657-8217 is being updated; the Berrien County Phone is not. The next Monday Fruit IPM Update meeting will be, Monday May 4, at the Fruit Acres Farm in Berrien County.
