Flower bud fatalities 100% - Stonefruit - Z 5b

@alan

Where can I find a daily record of temps for the area.

I relied on my next door neighbor and we spoke pretty much every day.

Each time he told me of a warm day, my question was " what did it do overnight?" wrongly figuring that as long as it went back down at night( much longer nights than days), the swift daytime spike did not matter.

Mike

Go to weather.com, they have observed high and low for past months.

or wunderground- it gives me data for my small town from a spot just 3 miles form me

Are you looking for recent data or past data or both? There are a few different spots to look…Weather underground is a good place to start…you can usually find something near where you live. I haven’t used it in awhile, but there is a site that has historic temp data, but its a little annoying to search. I have downloaded local data going back nearly a 100 years off that site…kind of neat to look at some of those really hot/cold stretches.

https://climate.usurf.usu.edu/mapGUI/mapGUI.php

Thanx guys

Mike

Zone 5b here as well, (60070)
My Sungold apricot is normally a fine producer, but we were threatened with several frosts and I sprayed KDL which worked for me last year (good for about 7 deg protection - Bob Purvis) Well it hit 22 degrees several times and low and behold we have perhaps 10% flowers, and probably no fruit set. Peaches, five trees, all had flowers but TBD on fruit set. Apples and Pears and cherries flowering now.

How does he know this- did he do a controlled study? If it was true I don’t think commercial growers would be spending thousands of dollars on the proven forms of frost protection. 7 degrees is a lot and news gets around.

One apple grower near me built bonfires between his trees and paid for helicopters to fly over his orchard all night during the late March temp nose dive. All that was needed there was a couple of degrees of protection.

Here’s a recent email I got from Bob regrading this…

"Hi Rob,

The spray I told you about is KDL, short for potassium (K) dextrose-lactose. You should order it directly from Agro-K Corp. in Minneapolis. Their toll-free number is 1-800-328-2418, and they are one hour ahead of the Mountain time zone. You can tell them that I recommended you to them. The cost of a one-gallon jug should still be $22 although you will have to pay for shipping as well. The rate I use is 3 oz KDL + 3 oz. household vinegar/gallon of water. You should only spray the tank mix lightly on your apricot trees; do not spray them to runoff as you might with other products. As I mentioned, at full bloom this should give you protection for 7-10 days if the weather is mild or 10-14 days if the temperatures are cool (daytime highs under 50F). Based on my experience here, the rate I quoted above should give 7-8 Fahrenheit degrees of protection at full bloom, or 3-4 Fahrenheit degrees of protection when the fruitlets are in the shuck. Once the fruitlets emerge from the shucks, under-tree sprinkling is the only thing that will protect them.

At red calyx stage (which is before the “popcorn” stage), the 10% and 90% mortality temperatures for 1/2 hour are 22F and 9F respectively; at full bloom, 27F and 22F respectively; in the shuck, 28 and 24F respectively; and once the fruitlets are out in the open, 28F and 25F. This is based on research at Washington State University back in the 1980s with commercial apricot cultivars. My experience in Selah and here shows that Puget Gold, Tomcot, Jerseycot, and the Harrow apricots except Harcot are above average in their frost tolerance relative to commercial cultivars such as Goldrich, Rival, Perfection, and maybe Robada.

I do not think it would be a good idea for you to have more than one of the cold-hardy apricots (Westcot, Morden 604, and Debbie’s Gold) as a pollenizer for Apache. A better focus for your selection of apricots would be those that are slow to respond to accumulation of heat units during the winter and early spring. Those specifically are Zard, Hoyt Montrose, Corbett, Alfred, Sugar Pearls, Montrose, and Jimmy Thomas (the apricot whose mother tree is 1 mile west of here). Their being later-blooming apricots will help somewhat in getting them through frosts. There is a good match between bloom time of Sugar Pearls and that of Harlayne and Jerseycot. Orange Red is average in its bloom time and response to fluctuating winter temperatures.

Be advised that Goldrich, Rival, Perfection, Apache, Orange Red, Harlayne, and Sugar Pearls require cross-pollination. Tomcot and Robada are partially self-fruitful. All the other apricots on my list are alluded to above are self-fruitful."

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