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

Featured Stories

All Vegetables Stories >All Fruits Stories >All Nuts Stories >All Citrus Stories >

The Latest

Crop ProtectionManaging Lepidoptera In Tomatoes
August 22, 2014
This video provides information on how to best identify and control Lepidoptera in tomatoes. Read More
GrapesMichigan Conference Focuses On Impact Of Climate Change…
August 22, 2014
Experts from Michigan State University, Ohio State University, and Northwestern Michigan College to discuss Polar Vortex, technology, and unmanned systems at one-day conference. Read More
GrapesNew York Grape Grower Survey Reveals Huge Losses
August 22, 2014
Cornell Cooperative Extension publishes results of a grower poll of winter injury damage. Read More
GrapesOregon Anticipates Large Grape Harvest
August 22, 2014
Growers keep fingers crossed that late-season rainfall doesn’t ruin crop. Read More
GrapesFarmers Fresh Fruit Company Integrates QR Code Into Cla…
August 22, 2014
Design allows consumers to access online information about variety, nutritional information, etc. Read More
Crop ProtectionGetting To The Root Of Good Soil Health Requires Some D…
August 21, 2014
Dave Gilliam of Horticultural Alliance says more citrus growers are paying attention to what's happening below the ground in their groves. Read More
Citrus‘Super Cold’ Winter, Sizzling Summer On Tap In 2015…
August 21, 2014
The 223rd edition of the folksy regional forecast manual predicting extremes. Read More
Insect & Disease UpdateMountains Of Data Being Used To Combat Citrus Greening
August 20, 2014
As HLB research evolves, new methods need to be developed to effectively utilize information. Read More
VegetablesAnnual Santa Maria Vegetable Meeting To Cover Progressi…
August 20, 2014
University of California Cooperative Extension will host annual vegetable meeting focusing on nutrient management, plant growth, weed management, and more. Read More
Leafy VegetablesTanimura & Antle Introduces New Lettuce Variety 
August 20, 2014
The California grower now offers George T’s Colossal Romaine Heart, in honor of the company's founder, George Tanimura. Read More
CitrusBorder Crisis Not Helping Farmers
August 19, 2014
As thousands cross into the U.S. seeking refuge, calls for ag labor reform are lost in the uproar. Read More
Cucurbits24 Sweet Watermelon Varieties [Slideshow]
August 19, 2014
Browse the slideshow below for information on 24 watermelon varieties from the nation’s leading seed breeders and distributors. Read More
FruitsHandheld Produce Quality Meter Debuts At 2014 Internati…
August 19, 2014
Researchers to present data measuring dry matter, color, and sugar content of cherries and other product pre- and postharvest. Read More
GrapesNew York State Assists Grape Growers Hit By Harsh Winte…
August 19, 2014
State to open winegrape market to grapes grown outside the state. Read More
FruitsEuropean Fruit And Vegetable Growers Hit By Russian Ban…
August 19, 2014
Angry at European Union/United States sanctions over Ukraine, Russia has banned many food imports. Read More
Apple Grower of the YearGet The Latest News On The Nation’s Apple Crop
August 19, 2014
American and Western Fruit Grower editors will be tweeting in real time this week from the Apple Crop Outlook & Marketing Conference. Read More
OrangesSour Forecast For 2014-2015 Florida Orange Crop
August 18, 2014
Paltry prediction signals lowest output in 50 years. Read More
Crop ProtectionBioConsortia Inc. Bolsters Executive Team
August 18, 2014
Industry veterans Christina Huben and Dr. Susan Turner bring experience to plant biotechnology firm. Read More