Pear Psylla Degree Days (updated weekly on Friday)

This page shows the cumulative pear psylla degree-days (DD) calculated by DAS at selected weather station locations across the Pacific North-West as part of the integrated pest management (IPM) program recently developer by the WSU Entomology Pear Extension and Research group at WSU-TFREC in Wenatchee, WA. The map below shows the most recently calculated cumulative DD values at each location.
The DAS calculated pear psylla degree-days, starting on the first week of February, will be available for free to the public for the 2023 season.

    Cashmere.N, WA Hood River, OR Medford, OR Omak, WA Peshastin.N, WA Wapato.W, WA Wenatchee, WA
Feb 3 7 39 120 0 8 12 6
Feb 10 16 61 152 0 13 25 16
Feb 17 26 78 169 0 19 43 27
Feb 24 48 99 186 3 31 66 48
Mar 3 52 101 194 4 33 77 56
Mar 10 53 107 205 5 33 83 56
Mar 17 70 128 243 14 43 108 74
Mar 24 111 167 280 48 74 152 116
Mar 31 150 196 301 80 103 182 157
Apr 7 182 223 337 104 123 219 190
Apr 14 230 265 397 146 158 272 241
Apr 21 269 298 444 180 185 313 284
Apr 28 376 409 573 273 281 424 401
May 5 540 527 678 452 432 576 576
May 12 664 647 767 567 536 697 712
May 19 863 857 961 763 724 915 919
May 26 1024 1001 1102 930 874 1090 1101
Jun 2 1202 1145 1250 1093 1023 1260 1306
Jun 9 1401 1316 1441 1289 1200 1474 1524
Jun 16 1592 1479 1620 1472 1371 1665 1736
Jun 23 1739 1608 1756 1604 1493 1805 1902
Jun 30 1962 1807 1953 1816 1696 2028 2142
Jul 7 2181 2020 2173 2034 1906 2254 2376
Jul 14 2412 2220 2384 2258 2113 2491 2625
Jul 21 2642 2440 2614 2485 2328 2718 2873
Jul 28 2863 2641 2830 2698 2523 2946 3110
Aug 4 3088 2840 3047 2914 2726 3155 3357
Aug 11 3308 3051 3267 3135 2926 3378 3598
Aug 18 3557 3292 3513 3386 3161 3617 3860
Aug 25 3735 3477 3720 3566 3325 3801 4054
Sep 1 3936 3667 3899 3764 3517 4002 4264
Sep 8 4124 3827 4073 3953 3690 4179 4472
Sep 15 4314 4014 4264 4129 3866 4368 4675

Learn more about the newly developed pear psylla management guidelines and phenology model at WSU Extension.
Subscribe to DAS to get daily degree-days values, including estimated forecasts, for any weather locations across Washington, Oregon and Idaho, together with timed management guidelines and spray recommendations throughout the season.