Pear Psylla Degree Days (updated weekly)

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 will be available for free to the public for the 2022 season.

    Cashmere.N, WA Hood River, OR Medford, OR Omak, WA Peshastin.N, WA Wapato.W, WA Wenatch.W, WA
Feb 28 56 114 296 6 48 92 55
Mar 7 99 162 336 25 78 146 95
Mar 14 123 198 388 40 95 183 123
Mar 21 165 234 429 72 124 226 167
Mar 28 253 326 535 140 201 315 259
Apr 4 311 380 596 192 246 377 323
Apr 11 351 413 656 232 273 417 365
Apr 18 363 433 683 247 280 431 381
Apr 25 427 488 742 301 331 495 453
May 2 493 548 807 362 383 559 531
May 9 572 620 875 439 442 642 624
May 16 650 703 961 508 505 734 713
May 23 747 797 1063 594 585 837 825
May 30 869 910 1185 711 682 949 958
Jun 6 1008 1062 1318 857 807 1106 1111
Jun 13 1151 1197 1472 999 936 1265 1274
Jun 20 1290 1323 1581 1135 1050 1400 1436
Jun 27 1477 1513 1779 1316 1221 1591 1644
Jul 4 1674 1687 1957 1505 1391 1800 1858
Jul 11 1868 1877 2163 1702 1566 2007 2069
Jul 18 2097 2078 2385 1922 1768 2228 2315
Jul 25 2334 2291 2601 2149 1988 2457 2568
Aug 1 2596 2548 2868 2401 2239 2716 2839
Aug 8 2809 2757 3104 2617 2438 2916 3071
Aug 15 3045 2964 3309 2857 2657 3146 3323
Aug 22 3304 3198 3535 3104 2901 3394 3594
Aug 29 3526 3410 3756 3317 3110 3603 3831
Sep 5 3750 3621 3976 3531 3319 3815 4066
Sep 12 3922 3802 4194 3694 3479 3983 4246
Sep 19 4074 3945 4342 3843 3619 4127 4408
Sep 26 4234 4111 4509 3995 3762 4276 4583
Oct 3 4401 4277 4675 4153 3922 4436 4762
Oct 10 4565 4446 4857 4306 4080 4594 4926
Oct 17 4694 4585 5013 4427 4201 4723 5060
Oct 24 4771 4671 5103 4489 4276 4799 5140
Oct 31 4828 4741 5168 4545 4320 4865 5203
Nov 7 4838 4763 5191 4553 4327 4890 5217
Nov 14 4838 4771 5210 4553 4327 4893 5218
Nov 21 4839 4771 5244 4553 4327 4894 5218
Nov 28 4839 4785 5265 4553 4328 4897 5219

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.