Category Archives: Weather

MaluSim Carbohydrate Models for May 16: Winchester and Central Virginia

MaluSim models were run on May 16 for Winchester and Central Virginia.

Slide4Slide3

As I spoke about at the Winchester breakfast meeting on Thursday morning, the Winchester forecast is calling for warm and cloudy weather starting today and running through most of next week. From many year’s of research, we know that these are the conditions under which there is a fair amount of natural thinning and that chemical thinners can be particularly active. When the weather data is run through the MaluSim model, we see that there is a carbohydrate deficit between -40 to -60 g CHO/day predicted for the next 10 days. This means that chemical thinners that are applied over the next several days will likely be fairly active. With this in mind, growers should consider reducing rates and/or not using a surfactant. Growers with blocks that sustained freeze damage on Tuesday morning, should consider further reducing rates. As always, you should be checking your trees and making decisions based upon the conditions in your own orchard.

For Central Virginia (Piney River), the carbohydrate deficits over the next week will remain in the negative, but not be as low as the Winchester area. This means that chemical thinners applied from today through the weekend will likely be slightly aggressive when used at standard rates. Growers should be regularly checking their blocks for current conditions. By now, you should be able to see some effect of the cloudy weather that the region experienced early last week.

Here are the pdf files that contain the weather data and the MaluSim models:

Peck Central VA MaluSim 5_16_13

Peck Winchester VA MaluSim 5_16_13

 

MaluSim Carbohydrate Models for May 9: Winchester and Central Virginia

Slide3

MaluSim carbohydrate models for Winchester and Central Virginia were run on Thursday morning.

Slide3

Over the next day or so, for Central Virginia, the carbohydrate balance will remain in the negative, but quickly move to the positive over the weekend. From thinning applications made Thursday (5/9) or Friday (5/10), growers should expect a fairly “normal” response. However, forecast data from Intellicast.com, suggests that sunnier, but cooler weather will move into Virginia early next week, followed by a warming trend starting on Wednesday. Based on the MaluSim model, this weather pattern will cause apple trees to have positive carbohydrate values through the early part of next week, and thus standard rates of thinners used on Saturday or Sunday will be less effective than expected. In blocks where heavier thinning is needed, growers should consider holding off on their 10 mm thinning application until Tuesday or Wednesday when warmer temperatures return. However, once fruit gets to be 15 mm or larger, NAA and 6-BA are less effective thinning agents. The other approach is to increase the rates used in thinning applications made over the weekend through Monday.

The above scenario is similar for Winchester but since fruit size is smaller (generally 6-8 mm), growers can wait for next week’s warming trend to make the 10 mm thinning applications. Additionally, with the smaller fruit size in Winchester, the cloudy weather that we’ve experienced over the last few days should cause less natural thinning than what might occur in Central Virginia.

I’ll run the model again on Monday.

Current fruitlet sizes at the Winchester AREC:

  • Empire: 8.0 mm
  • Golden Supreme: 6.3 mm
  • Fuji: 6.5 mm
  • Golden Delicious: 5.7 mm
  • Suncrisp: 6.0 mm
  • Pink Lady: 7.2 mm
  • Idared: 7.1 mm
  • York: 6.0 mm

For more information, download pdfs of the models:

Peck Central VA MaluSim 5_9_13

Peck Winchester VA MaluSim 5_9_13

MaluSim Carbohydrate Models for May 2: Winchester and Central Virginia

MaluSim Central VA 5_2_13

 

MaluSim Wincheter 5_2_2013

 

 

Today, I ran the first MaluSim Carbohydrate models for 2013. This includes a simulation for Winchester, and a simulation for Central Virginia (Piney River, VA). Thanks to Bennett Saunders for sending us the data to use for Central Virginia.

The Malusim model was developed by Drs. Alan Lakso and Terence Robinson at Cornell University to estimate the carbohydrate balance in an ‘Empire’ apple tree based upon many years of detailed research and information found in the scientific literature. In recent years, the model has been used by researchers and extension specialists in New York as a tool to help assess the application timing for applying thinning materials at the 10 mm fruitlet size. Carbohydrate status, and therefore the MaluSim model, is not as important for other times when chemical thinners might be applied (i.e., bloom, petal fall, 20 mm), so it is not as clear how well the model does to predict the response of chemical thinners used at timings other than 10 mm.

For the past several years, I have been running trials at the Winchester AREC to see how well the MaluSim model performs under conditions found in Virginia. Many researchers, including myself, are still working towards understanding the best way to use the model. From what we have found, when weather forecasts are used to predict the future carbohydrate status of an apple tree, the MaluSim model can provide a warning as to when there might be a chance for severe under- or over-thinning. This is particularly true when there are three- or four-day trends with large carbohydrate surpluses or deficits predicted. For this reason, in addition to the data points for each day, I show a four-day running average (the black line on the charts). To be consistent with other researchers and extension specialists, the four-day running average is calculated from the date the data is show to three days into the future.

Please keep these caveats in mind if you are using the MaluSim model to guide your thinning application timing:

  • We’re still learning how to best use the model. At this point, it is just one more tool in the toolbox. There is no tool that is better than your own experience with chemical thinning on your own farm.
  • Future predictions of carbohydrate status are based upon weather forecasts from Intellicast.com for Winchester and Piney River. Temperature forecasts are probably pretty good for 3-5 days, but cloud cover (which is how I calculate the future solar radiation) is much less reliable. Although I show predictions out 10 days, my confidence that they are correct decreases significantly after 5 days. Nonetheless, it is useful information–just remember to keep looking for updated models so that you have the most up-to-date information. I will do my best to post a model for Central Virginia and Winchester twice a week.
  • Look at the day that you want to spray, and the 2-3 days after that. If there are periods of severe surplus or deficit, consider adjusting the rates or timing of your thinning applications.
  • The model is based upon the phenology of ‘Empire’. This is because the researchers in NY had a large body of data on Empire to use when they created the model. Of particular note, you should be aware that the model “clock” starts at silver tip for Empire. Cultivars with much earlier or later bud break may not correlate as well with the model values.
  • The models that I am running use data from the Winchester AREC, and Saunders Brothers Orchards in Piney River, VA. You need to consider whether or not those locations represent the weather in your orchard.
  • The model only accounts for temperatures and sunlight. Other weather events, such as rainfall or frosts may cause other impacts on the efficacy of your thinning materials that are not going to be represented in the model.

In the below pdf files, I provide a chart of the weather data that are used to run each model (daily maximum temperature, daily minimum temperature, and daily solar radiation), a chart of the MaluSim model with day-by-day data and a four-day running average, and a chart with the potential response a chemical thinner might have for different levels of carbohydrate balance in the tree.

So, what do today’s models show? Some very advanced blocks of early blooming apple cultivars in Central Virginia are getting close to the 10 mm thinning stage. From applications that occur today and tomorrow, you should expect “normal” to “slightly aggressive” response from your standard thinning rates, but nothing that suggests sever overthinning. However, there is a period of unsettled weather predicted for Mon-Wed of next week that could cause the carbohydrate levels to drop in the trees. It all depends on the amount of cloud cover we get over those days. Temperatures are going to remain moderate over that period, so even with the potential for some cloud cover, it doesn’t look like a severe carbohydrate deficit. Cloud cover is the hardest thing to predict, and predictions are only good for 3 days at best.

In Winchester, we are still at late bloom to petal fall, so there’s probably another week before the carbohydrate model data needs careful interpretation.

I will talk more about the model at tonight’s In-depth fruit school in Winchester.

Peck Central VA MaluSim 5_2_13

Peck Winchester VA MaluSim 5_2_13

Potential for Cold Temperature Damage in Northern VA

The National Weather Service is predicting temperatures to drop to 22F by the morning of April 4 in the Winchester area. For the bud phenology that I’ve seen in the area, we will probably be spared from having very much damage.

Apples are still dormant with a few early blooming cultivars at silver or green tip. Even at green tip, there should only be 10% damage when temperatures drop to 18F. Peaches with a little pink showing may be susceptible to a low level ~10% of damage. Cherries are still in stage 1 or 2, and should be able to withstand temperatures down to 17F with minimal damage. So, fingers crossed that it doesn’t get any colder than predicted. Temperatures are forecasted to be more “spring-like” next week!

Here are pdf links for the Washington State University fact sheets on the critical temperatures for flower buds:

Additionally, Michigan State University has adapted the WSU critical temperature fact sheets into this easy-to-read fact sheet.

MSU has also put together an excellent set of resources about freezes and frosts in fruit crops.

Maturity Report — September 25, 2012

Cool weather over the region for the past week has helped space out the harvest for mid- to late-ripening apple varieties. Expect similar conditions, with a bit more rain over the upcoming week. Nonetheless, we’re still running 10 to 14 days early on the later ripening varieties.

In the Winchester area, Rome harvest is in full swing and York harvest is starting to ramp up.

Most Fuji strains are ready for harvest. This is probably the last week Fujis should be harvested for long-term storage.

Surprisingly, Granny Smith apples are ready for spot picking for long-term storage.

Stayman and Pink Lady apples are coloring very nicely, but have not yet started to develop varietal flavors.

Open this pdf to see the full dataset:

2012 Fruit Maturity Sept 25 (pdf)

Maturity Report — September 17, 2012

Harvest maturity report for Sept. 17:

2012 Fruit Maturity Sept 17 (pdf)

In general, the cool weather has greatly reduced fruit maturity over the past week. Along with today’s rain, this should give everyone a chance to catch their breadth. Other than a less than 50% chance of rain over the weekend, the next 10 days looks like excellent weather for picking. The cool nights have also further increased red color development. Overall, fruit quality seems to be very good this year.

At the AREC, Fujis, Romes, Idareds are ready for harvesting for long-term storage. Staymans and Yorks have not started to ripen on the trees yet.

Maturity Report — September 11, 2012

Here’s the latest maturity report using apples grown at the AHS Jr. AREC in Winchester or nearby:

2012 Fruit Maturity Sept 11

We’ve had adequate rainfall, which has helped overall fruit size in most orchards. Additionally, with the cooler night temperatures that we’ve been experiencing in the northern Shenandoah Valley, ripening has moderately slowed down which will allow for increased red color development.

Nonetheless, Reds, Goldens, early Fuji strains, and Empire without ReTain are ready for harvest and may be past their prime by the middle or end of next week. Many of these apples are already moving past the ideal starch readings for long-term CA storage.

Romes are probably going to be ready shortly (next week?), followed by Stayman and Idared. Additional fruit size increase will be gained for Yorks that are allowed to stay on the tree for a couple of more weeks.

Many of the blocks that we are collecting fruit from were sprayed with ReTain, so ethylene and starch readings in our reports are going to be lower than in non-sprayed blocks. As always, please check with your buyer before you harvest.

Annual End of August Apple Maturity Report

For 26 years, researchers at the Alson H. Smith, Jr. AREC have recorded Golden Delicious and Red Delicious apple maturity data from orchards based in and around Winchester. Data for Empire has been taken for ten years and for Gala for five years. In recent years, we have added other commercially important cultivars to the analyses in order to generate long term averages. These data provide an interesting insight into the current season’s harvest, and can help growers make decisions on when to pick different blocks.

Earlier this season, I discussed the potential for a very early harvest. Based on a model developed at Michigan State University, the first Red Delicious harvest was estimated to be August 27 in Winchester and August 25  in Central Virginia (see post from June 28). While extraordinarily early, this prediction may be fairly accurate. Red Delicious Brix are already at 11.9 (two brix units greater than the long-term average) and firmness is down to 18.2. I have already heard of Reds being picked in Central Virginia, but not yet in the Winchester area.

Another one of my concerns with this early season was the potential for there to be poor color development. This has not come to fruition, and in fact, on Red Delicious, Gala, and Empire red color is the highest it has ever been at this time of year. The cool nights predicted for the next 10 days, should further enhance color development.

Below are the data from this year’s end of August apple maturity sampling. In each year, the samples were taken around August 25 and consist of apples from the AREC and a few local growers. Thanks to Dave Carbaugh, Mark Sutphin, Rachel Marple, and Nick Leaverton for helping to collect and process the fruit. Please refer to my post from yesterday if you need help interpreting the different maturity indices. You can also download a pdf  of this data.

Golden Delicious Maturity Report 1986-2012

 

 
Year

Background Color (1-4)*

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)**

Ethylene (ppm)

Bloom Date

1986

2.2

19.5

12.7

1987

20.0

12.2

1988

18.6

11.0

1.5

1989

17.7

10.3

2.0

1990

18.0

10.5

1.6

1991

1.8

19.7

12.0

2.1

1992

1.8

20.1

12.0

1.6

1993

1.9

19.8

11.6

1.5

1994

2.3

19.8

12.0

1.7

1995

0.9

18.8

10.9

2.1

1996

2.9

19.6

11.2

2.9

1997

2.0

21.8

11.7

2.0

1998

2.5

19.2

12.2

2.1

1999

1.9

20.3

11.7

1.4

2000

1.8

17.5

11.9

2.5

2001

1.9

20.1

11.0

1.4

2002

2.2

21.2

11.4

2.1

2003

2.6

20.3

11.1

1.2

2004

2.3

18.2

12.3

2.0

2005

1.8

20.1

11.4

1.7

2006

1.9

18.5

12.4

1.8

2007

1.6

18.0

12.3

1.6

2008

2.1

18.3

12.9

1.6

22-23 Apr

2009

1.8

17.2

12.4

1.7

22-Apr

2010

1.6

18.6

12.9

1.4

13-Apr

2011

2.1

20.1

12.9

1.2

20-Apr

2012

2.5

18.5

12.5

1.3

0.00

2-Apr

Mean

2.0

19.2

11.8

1.8

16-Apr

Max

2.9

21.8

12.9

2.9

23-Apr

Min

0.9

17.2

10.3

1.2

2-Apr

* 1 = green, 2 = light green, 3 = yellowish green, 4 = yellow.
** 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

 


 


 

Red Delicious Maturity Report 1986-2012

Year

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

1986

72.0

18.8

11.2

1987

68.0

19.8

10.8

1988

54.0

18.4

10.0

1.6

1989

69.0

18.6

8.7

1.6

1990

73.0

18.1

8.9

1.5

1991

69.0

18.8

10.4

1.6

1992

76.0

20.8

10.2

1.3

1993

68.0

21.7

9.5

1.7

1994

68.0

19.7

9.5

1.9

1995

68.0

19.2

9.1

1.6

1996

62.5

19.3

8.9

2.0

25-Apr

1997

66.7

22.4

9.4

1.2

25-Apr

1998

81.9

19.3

9.9

2.5

15-Apr

1999

65.5

19.8

10.5

1.9

28-Apr

2000

87.4

16.2

9.6

2.3

11-Apr

2001

61.0

20.5

8.3

1.8

28-Apr

2002

60.2

21.4

9.4

2.1

22-Apr

2003

58.4

20.4

8.5

1.9

22-Apr

2004

88.2

16.7

10.0

2.3

20-Apr

2005

73.7

18.7

9.2

2.0

24-Apr

2006

63.8

18.7

10.7

2.0

16-Apr

2007

81.1

18.1

11.0

1.7

22-Apr

2008

86.6

18.1

9.4

2.0

22-Apr

2009

79.2

17.5

10.2

1.9

24-Apr

2010

65.9

18.2

11.5

1.7

8-Apr

2011

67.5

19.8

11.5

2.1

21-Apr

2012

92.5

18.2

11.9

1.8

0.03

29-30-Mar

Mean

71.4

19.2

9.9

1.8

19-Apr

Max

92.5

22.4

11.9

2.5

28-Apr

Min

54.0

16.2

8.3

1.2

29-30-Mar

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.


 

Gala Maturity Report 2008-2012

 

 
Year

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

2008

93.5

18.3

13.6

5.6

21-Apr

2009

86.8

17.5

13.4

4.5

22-Apr

2010

78.0

16.3

14.9

6.4

9-Apr

2011

77.5

19.4

13.7

4.9

19-Apr

2012

91.1

18.0

13.2

4.1

7.13

29-30-Mar

Mean

85.4

17.9

13.8

5.1

14-Apr

Max

93.5

19.4

14.9

6.4

22-Apr

Min

77.5

16.3

13.2

4.1

29-30-Mar

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

 

Empire Maturity Report 2002-2012

 

 
Year

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

2002

42.0

25.3

10.4

2.1

2003

60.4

21.9

9.6

1.7

2004

78.1

17.2

10.9

2.2

2005

55.3

20.3

10.1

1.9

2006

46.0

19.7

10.7

2.1

2007

64.0

17.9

10.6

2.1

2008

66.3

18.2

11.0

2.1

21-Apr

2009

52.4

16.6

10.9

1.1

20-Apr

2010

44.3

18.1

10.7

1.8

2011

49.8

19.7

11.2

2.0

2012

85.9

19.2

12.5

1.7

0.01

29-Mar

Mean

58.6

19.5

10.8

1.9

13-Apr

Max

85.9

25.3

12.5

2.2

21-Apr

Min

42.0

16.6

9.6

1.1

29-Mar

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

 

Maturity Report – Other Varieties 2012

 

 
Variety

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

Fuji Early Strain

65.5

16.7

14.65

4.1

0.03

5-Apr

Fuji Late Strain

30.0

20.9

12.1

2.1

0.03

5-Apr

Ida Red

36.7

17.0

12.3

1.3

0.00

2-Apr

Rome

39.8

22.5

12.3

1.5

.

12-Apr

York

41.8

22.4

10.7

1

0.00

3-Apr

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

MaluSim Carbohydrate Model for May 14

Here is the final MaluSim simulation for 2012 (pdf). Please let me know if you have any questions or feedback.

Also, we’re starting to see larger (+25 mm) fruit coming off of apple trees. Some of this fruit is abscising as a result of chemical thinning, but there also appears to be fruit that had either poor pollination (not all carpels have seeds) or had seeds that started to grow but died soon thereafter, possibly as a result of freeze damage. As you monitor your blocks for thinning responses, make sure to cut into the fruitlets and look at the seeds. Many of the fruitlets that have damaged or missing seeds are falling off the trees at the same time as those that were chemically thinned.

MaluSim Carbohydrate Model for May 10

Today’s MaluSim simulation for Winchester (pdf) confirms that the cloudy weather from the cold front that hung over the region for the past few days caused a carbohydrate deficit. The deficit was somewhat less severe than originally predicted, but resulted in similar enough data that I would not have changed the interpretation I provided on Monday. The difference in the predicted and the actual data was due to cooler daily max temps and more solar radiation than forecasted.  As I’ve mentioned previously, cloud cover forecasts are the least accurate and the most difficult to interpret.

Over the coming weekend, the model is showing a period of carbohydrate surplus, then another storm system is predicted for next week, which could cause another carbohydrate deficit.

On Monday, I will run the MaluSim model one last time for this season so that you can have a final version to reflect on as you assess the thinning in your orchards. Please provide me with feedback on how you used the model this season. Did it predict what you are seeing in your orchards? I would appreciate any comments that you think would be useful for improving the model for future years.