Having some snow on trees and ground, even if it is not that heavy like the one we had last night, is not bad at all. Having a layer of dry snow on the ground should provide good insulation for soil and roots against the expected low temperatures we will face tonight and tomorrow morning. Also, large limbs that are still loaded with snow should get some protection. Using sprinklers will worsen the situation as wet snow works as a good thermal conductor and will transfer these freezing temperatures to roots much faster than dry snow.
Category Archives: Uncategorized
Sprinklers for frost protection: are they worth using?
The simple and direct answer is YES, BUT you have to consider the right time/conditions.
When you use sprinklers to reduce frost damage, you are simply using the internal (latent) energy of water molecules as a source of heat to your trees. Simply, water exists in three forms (liquid, solid (ice) and gas (vapor), and the transition among these forms can produce energy (exothermic) or consume energy (endothermic) as appears in the diagram below. So, when the air temperature is below freezing points (< 32 oF), and you use sprinklers, you indeed encourage the transition of water from its liquid phase into ice in order to release the latent energy into sensible energy (heat) that plant tissues can use to warm up. Great! Where is the problem?
There are three things you have to understand and consider in order to get this positive effect of sprinklers and not to harm your plants. First, you have to watch the wind. The Wind encourages the transition of the water from the liquid phase into the gaseous phase (vapor) and while this happens, heat in the air and around your plants will be consumed in an endothermic reaction. So, it’s always recommended that you don’t use sprinklers if the wind is above (10 mph). The table below (Table 1) should help you decide the amount of water needed (inches/h) under different wind conditions (mph) and under different temperatures.
Table (1): Amount of water (inches/h) that should be provided for frost protection under different wind speeds (mph). (U of Florida Ext. Circ. 287)
Second is the dew point: without putting complication to the topic, low dew points implies low humidity and if the dew point is too low, the water you add through sprinklers will be soon evaporated to compensate for the low air humidity and consequently cools down air around your plants. So, under moderate dew points, a part of water you add through sprinklers will turn into vapor and consumes heat and another part will turn into ice and produces heat, but AFTER SOME TIME, the net energy will be positive and you will get the benefit of using sprinklers. However, if the dew point is too low, it means that the air is too dry and it will take MUCH TIME to be saturated with vapor. During this time, the air temperature might reach to the critical temperature at which your buds/flowers will be damaged. In this case, sprinklers will cause more damage to your plants than without sprinklers. To help you decide whether sprinklers will be useful for your case or not, use the following table (Table 2) to determine the temperature at which you should turn on/off your sprinklers. If the dew point and the critical damage temperatures are not in the range shown in the table, don’t use sprinklers.
Table (2) shows the minimum temperature at which sprinklers should be turned on/off (UC-Davis, FP005 Quick Answers).
Simply, select the critical temperature for frost damage (the columns) and the dew-point temperature (the rows). The temperature where the row value crosses with the column value is the minimum air temperature at which you can turn on/off your sprinklers.
– you can use this tool to determine the dew point (https://www.weather.gov/epz/wxcalc_rh).
Or, you can get the dew points from Intellicase (use your zip code) http://www.intellicast.com/Local/Weather.aspx?location=USVA0837
The third thing to consider is the amount of water that your sprinklers can provide. If you are not sure that your sprinklers can provide sufficient amount of water, don’t use them at all. Table (1) should help you determine the amount of water required under different conditions.
2017 Tree Fruit Research Priorities Questionnaire
Orchard management and profitable production of tree fruits has become driven by robust science and thorough research. In light of this fact, this multidisciplinary questionnaire has been put together by a group of AHS Jr.-AREC scientists to help them identify and set research questions that reflect the interests of Virginia tree fruit growers and stakeholders. A similar questionnaire was distributed 6 years ago and has served to guide AHS Jr.-AREC scientists designing their field-blocks and shaping their research directions. Based on this survey, many experiments in pomology, plant pathology and entomology have been initiated. This includes, but is not limited to, experiments on crop load management practices, orchard tree planting density, variety and rootstock evaluation, physiological disorders, fungicides and insecticide efficacy trials, mating disruption trials and organic practices. This year’s questionnaire is meant to investigate the new trends and interests of Virginia fruit producers that may ignite new ideas or further promote researching the existing ones.
We are expecting responses from tree fruit growers, private agricultural consultants, agribusiness field representatives, VCE specialists and VCE extension educators in Virginia. An online version of the 2017 questionnaire can be accessed here (https://virginiatech.qualtrics.com/SE/?SID=SV_ezHdupTmKNcdO05). Please complete before March 15th.
A paper version of this questionnaire will be distributed during the upcoming fruit school meetings (Feb 13-17).
2017 Tree Fruit Schools
Carroll Patrick Fruit School in Cana, Virginia: Monday, February 13, 2017 – agenda and registration details: ( carroll-patrick-fruit-school )
Botetourt-Roanoke Fruit School : Tuesday, February 14, 2017 – agenda and details ( roanoke-area-fruit-school )
Southside Fruit School in Blackstone, Virginia: Wednesday, February 15, 2017 – agenda and registration details: ( southside-fruit-school )
Nelson-Albemarle (Central Virginia ) Fruit School : Wednesday, February 15, 2017 – agenda and details ( 2017-fruit-school-registration-lovingston )
Rappahannock-Madison Fruit School in Syria, Virginia: Thursday, February 16, 2017 – agenda and details: ( rappahannock-madison-fruit-school )
Winchester Fruit School in Winchester, Virginia: Friday, February 17, 2017 – agenda and registration details: ( winchester-fruit-school )
2016 Spring Tree Fruit Meetings – Central Virginia
Central Virginia Tree Fruit Meetings:
Our first technical production meeting of the 2016 Central Virginia Orchard Meeting series begins on Tuesday, April 5th. It will be hosted by Henry Chiles and everyone at Crown Orchard. We will be meeting at the Johnson Purvis orchard block which is located just south of the village of Covesville. DIRECTIONS: From Charlottesville: Travel on Route 29 south for 15 miles (about 20 minutes). Approximately one mile south of Covesville turn left on Route 632 (Faber Road). From Lynchburg: Travel on Route 29 north. Approximately 1 mile north of the Nelson County line, at the top of the hill, turn right on Route 632 (Faber Road).
The orchard entrance is less than a quarter mile down the road. Turn left and cross the wooded railway trestle. The orchard is on the other side.
After the in-orchard portion of the program we will be provided lunch by the Chiles family. Since this is a catered lunch please let us know how many people are planning to attend by calling the Extension office at (434) 263-4035 or replying directly to this email. We owe many thanks to Mr. Chiles and his family for once again providing their hospitality to kick off another season of apple production.
This and all subsequent meetings will begin at 11:00 a.m. Please come to discuss fruit production issues and concerns with other fruit growers and Extension fruit specialists. Once again, please bring a bag lunch to our other meetings. Cold drinks will be provided by the host orchard.
2016 Orchard Meeting Schedule
Date Orchard
April 5th Crown Orchard
April 19th Silver Creek Orchard
May 3rd Saunders Brothers Orchard
May 17th Dickie Bros. Orchard
May 31st Fitzgerald Orchard
Sincerely,
Michael W. Lachance
Extension Agent
Lucinda A MacRae
Unit Administrative Assistant
Virginia Cooperative Extension
Nelson County Office
P.O. Box 298
8445 Thomas Nelson Hwy.
Lovingston, VA 22949
Tel 434-263-4035
Fax 434-263-4367
Email lmacrae@vt.edu
2016 Winter Fruit Schools – Save the Dates
The Patrick-Carroll school (Mt. Airy) will be held on Monday, Feb 8. The Botetourt-Roanoke school will be held on the morning of Wednesday, Feb 9, starting at 8:00 AM. A Blackstone school will be held this year, morning of Feb 10. The Nelson-Albemarle (Central Virginia) school will be held in the late afternoon-evening of that Wednesday, Feb 10, starting at 3:00 PM. The Madison-Rappahannock school will beheld on Thursday, Feb 11, and the Winchester school will be held on Friday, Feb 12. Details on the agendas will be posted when available.
http://www.virginiafruit.ento.vt.edu/HotApple.html
Annual End-of-August Maturity Testing
This it the 28th year that 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. Including 2013, data for Empire has been taken for twelve years and Gala for six years. In recent years, we have also 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.
As discussed in a previous post, bloom date was about three weeks later than in 2012 and fairly close to the long-term averages. This should mean that harvest dates will be relatively “normal” or at least more similar to harvest dates in the late 1990’s through early 2000’s than they have been in the last several years.
As of this week, most growers in the Northern Shenandoah region are finishing up picking Ginger Golds, and have started picking Gala and Honeycrisp. Some growers in Central Virginia are finishing Gala and starting with Golden Delicious.
Many of the Golden Delicious blocks that we tested this week had very nice fruit finish, with minimal russet. Golden Delicious maturity was quite variable in the blocks that we tested, and it appears that some blocks will be ready to harvest within the next week, while others are probably 7-10 days away from being ready to harvest. The use of ReTain by some growers may explain some of this variability.
With the cool nights that we have experienced in August, red skinned cultivars have developed better than average color. However, be sure to check the starch and sugar levels before picking to be sure that the apples are mature enough to pick. Many Red Delicious apples that we tested this week had great color but very little starch degradation and soluble solids were only at 9-10 Brix.
Below are the data from this year’s end-of-August apple maturity sampling. In each year, the samples were taken around August 25 (August 26 this year) and consist of apples from the AREC and a few local growers. Thanks to Dave Carbaugh and Abby Kowalski for collecting and testing the fruit. Please refer to my post from last year if you need help interpreting the different maturity indices. You can also download a pdf of the 2013 Annual August Maturity Report.
Golden Delicious Maturity Report 1986-2013 |
|
|||||
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 |
13.0 |
1.3 |
0.00 |
2-Apr |
2013 |
2.2 |
18.3 |
11.9 |
2.2 |
0.17 |
25-Apr |
Mean |
2.0 |
19.2 |
11.9 |
1.8 |
17-Apr |
|
Max |
2.9 |
21.8 |
13.0 |
2.9 |
25-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 1986-2013 |
||||||
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 |
92.1 |
18.2 |
11.9 |
1.8 |
0.03 |
29-30-Mar |
2013 |
91.3 |
18.4 |
9.8 |
2.0 |
0.25 |
23-Apr |
Mean |
72.1 |
19.1 |
9.9 |
1.8 |
0.1 |
20-Apr |
Max |
92.1 |
22.4 |
11.9 |
2.5 |
0.3 |
28-Apr |
Min |
54.0 |
16.2 |
8.3 |
1.2 |
0.0 |
29-30-Mar |
* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch. |
Gala Maturity Report 2008-2013 |
|
|||||
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 |
2013 |
91.1 |
18.0 |
12.4 |
5.4 |
1.71 |
23-Apr |
Mean |
86.3 |
17.9 |
13.5 |
5.2 |
4.4 |
15-Apr |
Max |
93.5 |
19.4 |
14.9 |
6.4 |
7.1 |
23-Apr |
Min |
77.5 |
16.3 |
12.4 |
4.1 |
1.7 |
29-30-Mar |
* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch. |
Empire Maturity Report 2002-2013 |
|
|||||
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 |
2013 |
63.0 |
18.6 |
10.6 |
1.5 |
0.04 |
21-Apr |
Mean |
59.0 |
19.4 |
10.8 |
1.9 |
0.0 |
15-Apr |
Max |
85.9 |
25.3 |
12.5 |
2.2 |
0.0 |
21-Apr |
Min |
42.0 |
16.6 |
9.6 |
1.1 |
0.0 |
29-Mar |
* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch. |
Maturity Report – Other Varieties 2011 |
||||||
Cultivar |
Red Color (%) |
Firmness (lbs) |
Soluble Solids (ºBrix) |
Starch-iodine Index (1-8)* |
||
HoneyCrisp |
66.2 |
15.8 |
13.0 |
5.1 |
||
Idared |
17.0 |
19.9 |
11.1 |
1.2 |
||
* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch. | ||||||
Maturity Report – Other Varieties 2012 |
|
|
||||
Cultivar |
Red Color (%) |
Firmness (lbs) |
Soluble Solids (ºBrix) |
Starch-iodine Index (1-8)* |
Ethylene (ppm) |
Bloom Date |
Fuji Early Strain |
65.5 |
16.7 |
14.7 |
4.1 |
0.03 |
5-Apr |
Fuji Late Strain |
26.0 |
20.9 |
12.1 |
2.1 |
0.03 |
5-Apr |
Idared |
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 |
0.00 |
3-Apr |
* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch. | ||||||
Maturity Report – Other Varieties 2013 |
|
|
||||
Cultivar (number of orchards tested) |
Red Color (%) |
Firmness (lbs) |
Soluble Solids (ºBrix) |
Starch-iodine Index (1-8)* |
Ethylene (ppm) |
Bloom Date |
Cameo (1) |
33.5 |
18.1 |
10.2 |
1.7 |
0.53 |
N/A |
Fuji Early Strain (2) |
80.3 |
16.3 |
13.6 |
4.3 |
1.51 |
25-Apr |
Ginger Gold (2) |
3.9** |
16.0 |
12.8 |
3.5 |
0.00 |
24-Apr |
Idared (6) |
41.1 |
17.5 |
10.1 |
1.2 |
0.12 |
23-Apr |
Jonagold (1) |
35.5 |
18.7 |
11.8 |
2.8 |
0.00 |
23-Apr |
Rome (1) |
21.2 |
24.6 |
9.2 |
2 |
0.00 |
1-May |
York (1) |
53.5 |
24.4 |
9.4 |
1 |
1.20 |
25-Apr |
* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch. | ||||||
** 1 = green, 2 = light green, 3 = yellowish green, 4 = yellow. |