| Background Information for this page | |||||||||||||||
| Return to radar list for Greenville RI | |||||||||||||||
| Chart version of thinner sensitivity ratings | |||||||||||||||
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| Estimated Apple Sensitivity to Chemical Thinners | |||||||||||||||
| Other factors
may outweigh the weather effects use for these estimates. Other
influences include: fruit diameter, fruit exposure to temperatures >=75 F,
pollination, this year's cropload, last year's cropload, warm February-early
April temperatures, frost and prolonged cool and cloudy weather during bloom,
previous fall weather, foliage condition last summer) Ratings below are for the influence of weather on fruit sensitivity to chemical thinning agents. Ratings assume fruit are less than 13mm diameter. Dates in bottom rows are beyond 18mm diameter for most cultivars, and are intended only for late cultivars. Look at your fruit! |
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| Rough guess McIntosh King fruit diameter
dates: 12mm - May 26, Thursday 15mm - May 28, Saturday 18mm - May 30, Monday |
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| Date after which fruit have exposure to 2 days of daily high temperature of at least 75 F: Wednesday, May 25 | |||||||||||||||
| Very warm night temperatures (average
> 69F = 19 heat units in table) can lead to "EXCESSIVE THINNING
RISK", especially if combined with cloudy weather, or if combined with
use of NAA. Warm nights + Cloudy days -----> Increased sensitivity, maximum thinning. Warm nights + Sunny days -----> Intermediate senstivity, moderate thinning. Cool nights + Cloudy days -----> Reduced sensitivity Cool nights + Sunny days -----> Reduced sensitivity, minimum thinning. |
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| THINNER
APPLICATION DATE Estimates assume morning application. For afternoon application use rating for next day. |
Average % CLOUD SHADING on application day and the next two days. < 20% = "sunny blue sky" > 40% = "cloudy" Cloudy weather on 3 days after application increases thinning. |
Average NIGHT HEAT UNITS = degrees above 50 F for 7pm--7am for 3 nights after application. Example: If average night time temperature is 55F, then value = 5. Values above 10 for three nights after application increases sensitivity to thinning. |
SUMMARY Influence of weather on sensitivity of fruit to thinning agents for 3 days following a morning application Ratings assume that fruit are within diameter range of susceptibility for thinning. |
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| McIntosh
95% Petal Fall Fri, May 13 |
sunny 5% | 1 | Reduced sensitivity | ||||||||||||
| 100% Petal Fall Sat, May 14 | 53% | 3 | Reduced sensitivity | ||||||||||||
| Sun, May 15 | 63% | 3 | Reduced sensitivity | ||||||||||||
| Mon, May 16 | 66% | 0 | Reduced sensitivity | ||||||||||||
| Tue, May 17 | 65% | 2 | Intermediate | ||||||||||||
| Wed, May 18 | 64% | 5 | Intermediate | ||||||||||||
| Thu, May 19 | 64% | 6 | Intermediate | ||||||||||||
| Fruit Set Fri, May 20 | 49% | 6 | Intermediate | ||||||||||||
| Sat, May 21 | 37% | 3 | Intermediate | ||||||||||||
| Sun, May 22 | 62% | 1 | Increased sensitivity | ||||||||||||
| Mon, May 23 | 66% | 11 | Increased sensitivity | ||||||||||||
| Tue, May 24 | 44% | 13 | Increased sensitivity | ||||||||||||
| Wed, May 25 | sunny 10% | 9 | Increased sensitivity | ||||||||||||
| Thu, May 26 | 35% | 15 | Stronger influence for Increased sensitivity -- fruit >12mm probably less sensitive to thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Fri, May 27 | sunny 11% | 17 | Stronger influence for Increased sensitivity -- fruit >12mm probably less sensitive to thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Sat, May 28 | 38% | 16 | Stronger influence for Increased sensitivity -- fruit >15mm may have minimal sensitivity due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Sun, May 29 | 30% | 19 | Stronger influence for Increased sensitivity -- fruit >15mm may have minimal sensitivity due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Mon, May 30 | sunny 19% | 18 | Stronger influence for Increased sensitivity -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Tue, May 31 | sunny 2% | 15 | Increased sensitivity -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Wed, June 1 | 28% | 16 | Intermediate -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Thu, June 2 | sunny 14% | 6 | Stronger influence for reduced sensitivity -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Fri, June 3 | sunny 13% | 4 | Reduced sensitivity -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Sat, June 4 | sunny 3% | 1 | Reduced sensitivity -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||