Monday, September 2, 2013

Precious Valley Water: Good to the Last Drop for Cotton Plants

For cotton growers, the Labor Day holiday offers little time for relaxing and lots of time working on plans for the upcoming harvest.

You can start counting the days for harvesters to arrive after cotton plants soak up the last precious drop of water. Around the San Joaquin Valley, the final irrigation cut off came last week. That means bolls are mature enough to ensure timely defoliation.

Cotton growers wrapped  irrigation at the end of August.
Normally, growers terminate irrigation a few days before the end of August.  The cut-off decision is based on the stage of cotton growth and amount of water in the soil.

As we said in the past, old-fashion plant mapping is the best way to keep track of plant development. In this case, growers can decide when to cut off water by counting the nodes above white flower (NAWF). In acala varieties, the count is five to six NAWF. Typically, you can expect about 20 percent of the crop above white flower to survive by harvest time.

Incidentally, Carlos points out that one grower wrapped up irrigation earlier than others because he had used up his water allocation for the season. You remember the dry winter and spring resulted in a skimpy 20 percent water allocation to many local growers, especially those in the Westlands Water District. For this grower, his plants are looking a little dry and stressed.

Elsewhere, though, cotton plants are loaded with 15 to 17 fruiting branches. You can see some fiber emerging from some of the cracked bolls.

Big-eyed bugs are beneficial insects. - UC IPM photo. 

On the pest front, whiteflies and aphids remain on the watch list. So far, there hasn’t been a major problem with the pests. There’s a good variety of beneficial insects such as big-eyed bugs, minute pirate bugs and green lacewings around in the field.

In alfalfa, growers have completed their fifth cutting and should be irrigating their fields again this week. The sixth harvest is just around the corner.

Some almond growers are treating for navel orangeworm.

For almond growers, the harvest is in full swing. They are preparing to shake the nuts off the trees for a second time. Some growers are worried about navel orangeworm damage to their soft shell varieties and plan to spray their orchards before the final shaking. These are farmers who have large orchards and potentially could suffer hefty financial losses from NOW damage. Overall, though, field scout Jenna Horine says pests are under control.

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