Dealing With Puncturevine In Nuts

Puncturevine Weevil Pupae

Some may think I am a little crazy to harvest a puncturevine (PV) plant and count all of the seeds that it produces; however, that is what I did last year to make a point about puncturevine weevils.

Growers may recall back in the 1960s and 1970s when puncture-vine weevils (Microlarinus lareynii) were available for release in fields where PVs were a problematic weed. These parasites were native to India and Europe, and were introduced into the U.S. in 1961. They did a very good job of becoming established and parasitizing PV seeds. The question keeps arising, though: “Why aren’t PV weevils available to release or purchase?”

Actually, there still are commercial companies that offer PV weevils for sale; however, close examination of existing PV plants in the late summer will reveal that the weevil populations are doing quite well. There is another PV weevil (Microlarinus lypriformis) that feeds on the bottom side of the PV stems, but it is the seed-feeding weevil that does the most to suppress the PV populations. The key word is suppress. This weevil on its own cannot eradicate PVs.

Female PV seed weevils chew through the side of green PV seed capsules and deposit eggs. The larvae develop inside of the seed and pupate. The adult emerges in about three weeks in central California. There are multiple generations per year based on local temperatures. So why don’t these weevils eliminate PVs? The answer is all in the numbers, and this gets back to me counting seeds.

I have read in the literature that a typical PV plant can have up to 5,000 seeds. The particular plant I counted had a 4-foot diameter and had 28,896 seeds. Of that, 45% (13,003) were parasitized by PV seed weevils. That means that of the original 28,896 seeds, 15,893 were still viable. If each seed produced a plant that yielded the same number of seeds as the mother plant, that would mean this plant could yield more than 459 million seeds. We all know that 100% of the seeds won’t grow into the same 4-foot diameter plant. However, even if only a few do, it illustrates how rapidly PV can proliferate, even when 13,000 seeds on the original mother plant were parasitized by the weevil.

The reality is that PV seed weevils are widely present and doing a good job of feeding on PV seeds. Examination of mature plants in late-summer will reveal their activity. It’s just that, as with most parasites, they only suppress the target to levels that require additional management. Cultivation or herbicides are necessary to complement the PV weevils in their effort to control PV.

Leave a Reply

Nuts Stories
Photo credit: USDA
Citrus
May 23, 2016
World Health Organization Experts: Glyphosate Not Carcinogenic
Risk unlikely when consuming crops treated with herbicide. Read More
nutcracker crunching down on a walnut
Nuts
May 20, 2016
Bank Predicts A Roller Coaster Ride For Tree Nut Industry
Supply expected to grow by more than one-third in next five years, but decreasing demand may lower prices. Read More
close-up of a merge ahead traffic sign
Citrus
May 19, 2016
Bayer Makes Bid For Monsanto
Monsanto says proposal is being reviewed by board of directors as well as legal and financial advisors. Read More
(Photo credit: USDA)
Citrus
May 17, 2016
$130 Million In Funds For Fruit And Vegetable Education And Research
USDA allocates funds for Extension, organic production, food safety, and technology grants. Read More
A two-spotted spider mite. (Photo credit: www.bugwood.org)
Insect Control
May 16, 2016
Tips For Balancing Almond Mites And Predators
Almond growers need to do a delicate dance to keep spider mite populations down, but not so far that beneficial Read More
Almonds
Nuts
May 14, 2016
Almond Hullers And Processors Association Rebrands, Retools
The Almond Hullers and Processors Association (AHPA) renamed itself the Almond Alliance of California at its annual convention in April, Read More
handshake feature image
Fertilizer
May 13, 2016
Northeast Ag Sales To Distribute Agro-K Fertilizer Products
Partnership to all New England states enhanced access to full line of foliar plant nutrition and soil biological items. Read More
The Latest
Insect Control
May 26, 2016
Temperature, Location Key To Predicting …
This year, leaffooted bugs are expected to be a significant problem in almonds and pistachios, but watching temperature and the Read More
Fruits
May 26, 2016
Consider Fumigating For Nematodes Before…
Stone fruit and almond growers looking to replant orchards might want to invest in soil samples to assess nematode populations Read More
Citrus
May 25, 2016
Monsanto Says Bayer Bid ‘Financially Ina…
Proposal cited as undervalued, not able to address financial, regulatory risks. Read More
Citrus
May 23, 2016
World Health Organization Experts: Glyph…
Risk unlikely when consuming crops treated with herbicide. Read More
Nuts
May 20, 2016
Bank Predicts A Roller Coaster Ride For …
Supply expected to grow by more than one-third in next five years, but decreasing demand may lower prices. Read More
Citrus
May 19, 2016
Bayer Makes Bid For Monsanto
Monsanto says proposal is being reviewed by board of directors as well as legal and financial advisors. Read More
Citrus
May 17, 2016
$130 Million In Funds For Fruit And Vege…
USDA allocates funds for Extension, organic production, food safety, and technology grants. Read More
Insect Control
May 16, 2016
Tips For Balancing Almond Mites And Pred…
Almond growers need to do a delicate dance to keep spider mite populations down, but not so far that beneficial Read More
Nuts
May 14, 2016
Almond Hullers And Processors Associatio…
The Almond Hullers and Processors Association (AHPA) renamed itself the Almond Alliance of California at its annual convention in April, Read More
Fertilizer
May 13, 2016
Northeast Ag Sales To Distribute Agro-K …
Partnership to all New England states enhanced access to full line of foliar plant nutrition and soil biological items. Read More
Fruits
May 10, 2016
California Governor Signs Executive Orde…
Rule updates existing requirements for agriculture water management plans. Read More
Citrus
May 10, 2016
Survey: Beekeepers Lost 44% Of Bees Last…
Responses indicate summer losses rival winter losses for second year in a row. Read More
Citrus
May 4, 2016
$6 Million Available For Antimicrobial R…
Program to develop strategies to reduce public health risks in food chain. Read More
Nuts
May 2, 2016
California Almond Acreage Up 6%
The increase follows a trend in which acreage has doubled in the last 20 years. Read More
Nuts
April 29, 2016
Look Out For Jacket Rot On Almond Leaves
Rains at bloom are causing higher than normal incidents of bacterial infections. Read More
Citrus
April 26, 2016
Farm Bureau Says Labor Visa Backlogs Thr…
Agency calls for swifter processing of paperwork so growers' requests for crews can be met. Read More
Equipment
April 22, 2016
Whole Orchard Recycling Could Improve So…
A giant new machine gobbles up whole trees and spits out the chunks, which eventually get worked back into the soil. Read More
Nuts
April 20, 2016
California Legislators Give Preliminary …
California experienced 158 cargo theft incidents in 2015, costing businesses nearly $19 million – more than any other state. Read More
[gravityform id="62" title="false" description="false"]