Share this:

The Canterbury Psyllid Liberibacter Initiative can be read about in full here https://potatoesnz.co.nz/rd-project/canterbury-psyllid-liberibacter-initiative/ The CPLI Degree Day Graphs are one of the activities from this project.

Name Downloads
Name Downloads
9 downloads
5 downloads
6 downloads
15 downloads
15 downloads
15 downloads
12 downloads
13 downloads
17 downloads
25 downloads
26 downloads
19 downloads
27 downloads
26 downloads
28 downloads
23 downloads
19 downloads
21 downloads
24 downloads
26 downloads
26 downloads
30 downloads
31 downloads
37 downloads
33 downloads
37 downloads
33 downloads
35 downloads
33 downloads
36 downloads
36 downloads
37 downloads
37 downloads
38 downloads
38 downloads
40 downloads
35 downloads
46 downloads
41 downloads
34 downloads
39 downloads
37 downloads
44 downloads
49 downloads
49 downloads
168 downloads
143 downloads
144 downloads
162 downloads
149 downloads
147 downloads
155 downloads
148 downloads
137 downloads
148 downloads
169 downloads
157 downloads
174 downloads
177 downloads
155 downloads
178 downloads
141 downloads
164 downloads
175 downloads
173 downloads
174 downloads
170 downloads
172 downloads
150 downloads
148 downloads
155 downloads
165 downloads
152 downloads
154 downloads
170 downloads
164 downloads
171 downloads
166 downloads
162 downloads
169 downloads
148 downloads
187 downloads
176 downloads
169 downloads
175 downloads
168 downloads
193 downloads
185 downloads
173 downloads
164 downloads
181 downloads
185 downloads
188 downloads
197 downloads
176 downloads
181 downloads
192 downloads
182 downloads
209 downloads
180 downloads
219 downloads
25th October 2022 Chertsey
200 downloads
282 downloads
189 downloads
17th October 2022 Chertsey
194 downloads
260 downloads
279 downloads
267 downloads
298 downloads
14th March 2022 Lincoln
264 downloads
293 downloads
290 downloads
281 downloads
283 downloads
300 downloads
291 downloads
292 downloads
283 downloads
286 downloads
278 downloads
301 downloads
284 downloads
310 downloads
302 downloads
437 downloads
293 downloads
320 downloads
334 downloads
310 downloads
297 downloads
296 downloads
299 downloads
310 downloads
326 downloads
316 downloads
278 downloads
294 downloads
317 downloads
298 downloads
317 downloads
300 downloads
313 downloads
324 downloads
286 downloads
325 downloads
327 downloads
325 downloads
306 downloads
310 downloads
299 downloads
338 downloads
308 downloads
327 downloads
298 downloads
329 downloads
314 downloads
301 downloads
289 downloads
297 downloads
314 downloads
317 downloads
313 downloads
330 downloads
307 downloads
322 downloads
295 downloads
330 downloads
301 downloads
323 downloads
286 downloads
286 downloads
311 downloads
328 downloads
355 downloads

These following graphs show accumulated degree days (DD) for Pukekohe, Hawke’s Bay, Manawatu, Mid-Canterbury and South Canterbury from 2014-2020. The graph for each region also contains accumulated degree days for a hot and cold year in that region, to allow you to make comparisons with the current season. The number of psyllid (TPP) generations for the current season so far is indicated on the graph with a yellow arrow.

Name Downloads
Name Downloads
2 downloads
1 downloads
2 downloads
613 downloads
563 downloads
537 downloads
580 downloads
606 downloads
600 downloads
598 downloads
535 downloads
535 downloads
641 downloads
571 downloads
575 downloads
576 downloads
589 downloads
558 downloads
563 downloads
560 downloads
556 downloads
595 downloads
584 downloads
767 downloads
617 downloads
586 downloads
599 downloads
624 downloads
582 downloads
575 downloads
656 downloads
647 downloads
602 downloads
738 downloads
663 downloads
655 downloads
623 downloads
630 downloads
674 downloads
658 downloads
631 downloads
687 downloads
656 downloads
774 downloads
643 downloads
648 downloads
632 downloads
637 downloads
704 downloads
637 downloads
658 downloads
719 downloads
686 downloads
740 downloads
649 downloads
654 downloads
615 downloads
765 downloads
606 downloads
700 downloads
Using Degree Days to Time Treatments for Insect Pests
1056 downloads
695 downloads
634 downloads
672 downloads
794 downloads
649 downloads
628 downloads
688 downloads
687 downloads
664 downloads
618 downloads
628 downloads
637 downloads
661 downloads
608 downloads
612 downloads
633 downloads
677 downloads
671 downloads
650 downloads
673 downloads
626 downloads
635 downloads

Name Downloads
Name Downloads
460 downloads

About Degree Days

Insecticides that are applied for a perennial insect pest based on a calendar date often result in poor insect control and a waste of resources. Insect activity varies from year to year depending on weather.

As long as accurate weather data can be obtained, using degree days to time treatments is more reliable than a calendar date and allows growers to pinpoint a specific treatment date each year.

Degree days (often referred to as “growing degree days”) are accurate because insects have a predictable development pattern based on heat accumulation.

Every insect requires a consistent amount of heat accumulation to reach certain life stages, such as egg hatch or adult flight. Degree day values interpret that heat accumulation. When used to determine treatment timing, they are an important component of an Integrated Pest Management program, providing a cost-effective tool to reduce insect feeding damage (See Figure 1).

Things to consider:

Psyllids are active throughout the year and therefore 1 July is an arbitrary starting point.

It is important to be aware of other plants near your crop that can sustain TPP and act as a source of infestation. These include nightshade weeds, African boxthorn, poroporo but also volunteer potatoes.

* Since the psyllid research is a work in progress, we strongly advise you to use the degree day graphs in conjunction with crop monitoring using sticky traps and plant sampling. Crop monitoring provides valuable information on TPP arrival, population build up and the life stages present in your crop (see the links below for a sticky trap monitoring brochure).

What do you need to know about insects and degree days?

Insect growth and development

Since insects are cold-blooded, temperature plays a major role in their growth and development. Insects require a certain amount of heat to develop from one stage in their life to another i.e. eggs – nymphs – adults. Insects have a lower development threshold below which insect development is negligible and an upper development threshold which is the maximum temperature before development stops. These thresholds can be used in predicting insect development.

Further Information

Using Degree Days to Time Treatments for Insect Pests by Marion S. Murray, Utah State University.

Understanding Degree Days by Gabriella Zilahi-Balogh and Douglas G. Pfeiffer, Virginia Polytechnic Institute and State University.

Spraying: Unfortunately, the potato psyllid is a difficult pest to control. Spraying can be reasonably effective but it’s essential to cover all parts of the plant thoroughly with spray. This can be difficult because potato plants have dense foliage later in the growing season. If you do spray, remember to follow all aspects of Good Agricultural Practice, including spraying guidelines ensuring you don’t spray too close to harvesting time. Also, make sure you follow resistance management guidelines to prevent psyllid becoming resistant to the sprays.

Weeds: Another control is to keep down or eradicate other plants that are alternative hosts to psyllid. These include common weeds such as convolvulus, jimson weed (thornapple), mallow, African boxthorn (Lycium ferocissimum and black nightshade. Ornamental solanaceous plants are also potential hosts, and so is the native plant poroporo. Removing these plants from around your potatoes may reduce the likelihood of psyllid.

Contact

For further information please contact Natasha Taylor, Research Associate, Plant and Food Research, ph: (06) 975 8880