Welcome to our Ag Blog. Our field scouts will offer a unique ground-level perspective from the field to you as an independent field scout with the San Joaquin Sustainable Farming Project. Our mission is to promote sustainable farming systems throughout the Central Valley and provide you with the latest information about cotton, almond and alfalfa crops. From time to time, you'll also find guest posts from our project team and other contributors. This Blog is produced by Gilbert Mohtes-Chan.
Monday, July 2, 2018
Patience, Second Look Pays Off for the Pocketbook and Environment in the Valley
pest numbers were up. The grower was worried.
dilemma at this crucial stage in the development of his cotton plants:
he move ahead and treat his field with pesticides to control the potentially
crop-damaging bugs? Or should he wait a bit longer, hope the pests go away and
avoid treating the field – a move that could risk a population explosion that
ultimately could damage his yield at harvest.
Growers weigh decisions on treating their field for pests.
is real life drama in the Valley – no mocked up reality TV show.
let’s set up the situation. Earlier pest monitoring reports indicated a higher
than desired count for lygus bugs populating his field. Lygus, as many cotton
growers know, can cause big-time damage to developing cotton bolls.
wanted to spray for the pests,” field scout Damien Jelen says.
before making that final decision, the grower and Damien rendezvoused at the
field. Damien pulled out his trusty sweep net and canvassed the field.
found one count,” Damien recalled. Translated: Out of 50 passes of his sweep
net, Damien snared only one lygus bug – way below the numbers from previous
field visits and well below the threshold UC Integrated Pest Management
recommends for treating for lygus in cotton.
decision: Hold off spraying.
patience does pay off. And having Damien provide another set of eyes to
supplement monitoring by the grower’s pest control adviser can certainly yield
dividends. As in this case, it can avoid an expensive pesticide treatment while
keeping chemicals out of the environment.
Sweep nets will catch pests populating a field.
For field scouts like Damien, the key tool of his field
scouting practice is no fancy high-tech gadget. It’s a sweep net – akin to a
heavy-duty, oversized butterfly net.
Using it in the field to collect pest
samples takes practice to ensure results from different practitioners produce
In cotton, for example, sampling for lygus starts when the
cotton plant develops its first square. Samples should be taken twice a week. UC
IPM recommends sampling each quarter of a field and taking even more samples in
fields larger than 8 acres. Do 50 sweeps across one row of cotton to sample for
lygus, making sure the sweeps don’t overlap. Lygus monitoring can end when
have 5 nodes above white flower and Pima has 3.5.
It’s common for people to sweep from
right to left and then step forward and sweep again left to right. After 5
sweeps, you pull the net through the air to push the bugs into the bottom of
the net bag. UC IPM recommends taking a sample in four different spots in a
If it’s hard to count the bugs while in
the field, place the insects in a bag and cool the contents to slow done pest
movement.UC IPM provides
information about treatment thresholds for various pests.
lygus counts jumped up as the early summer heat took hold, Damien says the
numbers leveled out in the past week. So far, Damien hasn’t seen many signs of
a large number of damaged cotton squares on the ground.
course, there are still some four months – and a long summer – left until the
harvest. You can be sure Damien and growers will remain vigilant until then.