| Background Information for this page | |||||||||||||||
| Return to radar list for Greenville RI | |||||||||||||||
| Chart version of thinner sensitivity ratings | |||||||||||||||
|
|||||||||||||||
| 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! |
|||||||||||||||
| Rough guess McIntosh King fruit diameter
dates: 12mm - May 15, Tuesday 15mm - May 18, Friday 18mm - May 21, Monday |
|||||||||||||||
| Date after which fruit have exposure to 2 days of daily high temperature of at least 75 F: Sunday, May 13 | |||||||||||||||
| 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. |
|||||||||||||||
| 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. |
||||||||||||
| McIntosh
95% Petal Fall Thu, April 26 |
23% | 2 | Stronger influence for reduced sensitivity | ||||||||||||
| 100% Petal Fall Fri, April 27 | sunny 19% | 0 | Stronger influence for reduced sensitivity | ||||||||||||
| Sat, April 28 | sunny 2% | 0 | Stronger influence for reduced sensitivity | ||||||||||||
| Sun, April 29 | sunny 1% | 0 | Stronger influence for reduced sensitivity | ||||||||||||
| Mon, April 30 | sunny 3% | 0 | Stronger influence for reduced sensitivity | ||||||||||||
| Tue, May 1 | 66% | 0 | Stronger influence for reduced sensitivity | ||||||||||||
| Wed, May 2 | 67% | 0 | Reduced sensitivity | ||||||||||||
| Thu, May 3 | 69% | 0 | Reduced sensitivity | ||||||||||||
| Fri, May 4 | 62% | 3 | Reduced sensitivity | ||||||||||||
| Fruit Set Sat, May 5 | 62% | 1 | Stronger influence for reduced sensitivity | ||||||||||||
| Sun, May 6 | 34% | 1 | Reduced sensitivity | ||||||||||||
| Mon, May 7 | sunny 6% | 3 | Intermediate | ||||||||||||
| Tue, May 8 | 59% | 6 | Intermediate | ||||||||||||
| Wed, May 9 | 66% | 7 | Reduced sensitivity | ||||||||||||
| Thu, May 10 | 50% | 1 | Reduced sensitivity | ||||||||||||
| Fri, May 11 | 27% | 2 | Reduced sensitivity | ||||||||||||
| Sat, May 12 | sunny 0% | 9 | Intermediate | ||||||||||||
| Sun, May 13 | sunny 8% | 11 | Increased sensitivity | ||||||||||||
| Mon, May 14 | 34% | 10 | Increased sensitivity-- sensitivity may be less because of fruit exposure to 2+ days with high temps. > 75F | ||||||||||||
| Tue, May 15 | 43% | 11 | Intermediate -- fruit >12mm probably less sensitive to thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Wed, May 16 | 59% | 8 | Reduced sensitivity -- fruit >12mm probably less sensitive to thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Thu, May 17 | sunny 2% | 2 | Stronger influence for reduced sensitivity -- fruit >12mm probably less sensitive to thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Fri, May 18 | sunny 4% | 2 | Reduced sensitivity -- fruit >15mm may have minimal sensitivity due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Sat, May 19 | sunny 1% | 5 | Intermediate -- fruit >15mm may have minimal sensitivity due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Sun, May 20 | sunny 3% | 6 | Intermediate -- fruit >15mm may have minimal sensitivity due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Mon, May 21 | 64% | 10 | Increased sensitivity -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Tue, May 22 | 73% | 7 | Increased sensitivity -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Wed, May 23 | 45% | 11 | 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 | ||||||||||||
| Thu, May 24 | 32% | 15 | 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 | ||||||||||||
| Fri, May 25 | 40% | 18 | EXCESSIVE THINNING RISK -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||
| Sat, May 26 | 34% | 20 | EXCESSIVE THINNING RISK -- fruit > 18mm are probably beyond predictable chemical thinning due to size and exposure to 2+ days with high temps. > 75F | ||||||||||||