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Field Experiments

 

How Flower Strips Can Improve Squash Pollination and Yields​

 

My first field experiment focused on on-farm floral plantings can change pollination and translate into fruit set and crop yield. In this experiment, I planted flower strips in a randomized block design throughout 2 squash farms (Sam Accursio and Sons located in Homestead, Florida). I examined insect visitation to the flower blocks (Sweet Alyssum- Lobularia maritima, white variety and Buckwheat, Fagopyrum esculentum, variety Koku, two well-studied commonly used insectary plants to attract beneficial insects). I tracked squash plants at close, medium, and far distances from these flower blocks to see how proximity affected squash pollination, and measured zucchini production, weather, and fruit abortion rates. These results found squash plants near the flower strips, especially Buckwheat, produced significantly more zucchini. By pairing direct pollinator observations with final yield outcomes, this experiment links behavioral responses of pollinators to measurable changes in crop performance, providing a field-based perspective on how farm management affects pollination-dependent food production.

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The farming collaborator for this project (Sam Accursio) has continued floral plantings in his fields, adding different mixtures and locations to improve spring time pollination of squash, when bees tend to prefer tropical fruit trees to his zucchini plants. He has continued to see improvements in his yields!

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Experimental Warming of Squash Effects on Plants and Pollinators

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My second field experiment examines how heat stress influences zucchini squash (Cucurbita pepo) flowering and pollinator visitation under natural growing conditions. Using in-field temperature manipulations called Open Top Chambers (OTC'S), I measured how elevated temperatures affect flower production, male–female flower ratios, and pollinator activity throughout the flowering period. I conducted repeated pollinator observations to quantify visitor abundance, visitation rates, and species composition, allowing me to assess how warming alters real-time plant–pollinator interactions in an open agricultural setting.

 

These experiments were conducted on a conventional squash farm (Sam Accursio and Sons in Homestead, FL) and an Organic (French Farms, Redlands, Florida) to see how different landscapes may buffer heat stress on plants and pollinators. These results saw higher pollinator visitation and overall yields in the organic farm versus conventional, however no difference between plants inside the OTC's versus control.

Lab Experiment: How Heat Stress Affects Zucchini Squash and its Bumblebee (Bombus impatiens) Pollinators

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Conducted with Kenneth Feeley at the University of Miami and the International Center for Tropical Botany

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To isolate the direct physiological effects of heat stress, I conducted controlled growth-chamber experiments exposing zucchini plants and pollinators to experimentally elevated temperatures. These experiments allow me to separate temperature effects from other environmental variables present in the field. I measured flowering dynamics, nectar volume and sugar concentration, pollen traits, and plant structural responses under different warming scenarios.

 

In parallel, I conducted laboratory assays on pollinators to examine how heat exposure influences behavior and performance. These experiments include measurements of foraging activity, visitation patterns, and physiological stress responses, helping to clarify the mechanistic pathways through which temperature alters pollination processes. Together, these lab and growth-chamber experiments provide the mechanistic foundation that complements and strengthens my field-based findings.

ORAL HISTORY QUESTIONNAIRE WITH COMMERCIAL SOUTH FLORIDA SQUASH GROWER

 

Pre-Experiment Questions

 

1.     How long has your family been in the farming industry?

Since 1948, grandfather started east of Honda dealership (NE 1ST Ave and NE 7TH St) in Homestead, Florida. Flooding issues at this location so moved to West pine where they scarifed the land for farming using D8 caterpillar tractors. To farm this land was highly input intensive. In 1970s University of Florida invented chlorine production of produce to help produce last longer, led to regulations now chlorine dioxide in production.

 

2.     What crops do you/ have you grown?

Tomato, strawberry, corn, pickles, squash, okra, and green beans. This combined leads to trailer load of produce for shipments.

 

3.     How large is your production system (distribution/customer size etc)?

They supply 8 chain stores from local to international. Supply to Montreal and East Coast mostly. They load from packing house in Homestead and supply annual 20 million lbs of produce to about 40 million customers. They donate to farm share anything that is unusable such as scratched produce, and the rest gets thrown into dump.

 

4.     Have you experienced an impact on growing due to adverse weather?

The historic snow in 1977 they lost everything. 1989 Christmas cold front also resulted in total loss. For about last 10 years less frequent frosts around the 30°F. Historically, there used to be 10 times a year you would hit that temperature (30°). Rainy and cloudy weather and more extreme weather in winter such as hail has also caused losses, 160 acres were lost around 40 years ago because of hail storms. Drier summers are also bad and affect losses. Heat breaking records are also affecting crops. Crops grow too fast in high heat causing a shorter season. No longer is the growing season October through May, it’s now November through April. Still though winter production is profitable.

 

5.     Have you experienced an impact on growing due to pollination issues?

Windy, cool, damp, and wet weather leads to a loss in pollination and squash. They experience serious issues with pollination in March when the honey bees they bring in leave the squash fields to visit more attractive co-flowering crops nearby (avocado/mango). They experiment with spraying sugar honey and bee attractant on the crop as well as tried using commercial bumblebees as pollinators but were unsuccessful. The commercial bumblebees didn’t leave the hive, possibly due to weather.

 

6.     What are some stressors you face growing crops related to climate change? 

They have seen the loss of a month on each end of the season due to shifting temperatures (now only November-April, prior growing season in South Florida was October-May). They also have labor issues, with the requirement to be more productive in this shorter season. Now with only six to seven months were they need laborers, it is shorter and less inviting for workers to come to the United States. Most workers come from Mexico, go up and back down from Maine to harvest blueberries down to South and Central Florida in April then back to Mexico.

 

7.     Has growing changed over your families’ generations due to climate change and pollination changes?

No, growing has remained the same for the most part related to pollination. They have always brought in bees depending on crop needs and weather. The decisions now are whether to bring in more bees to help increase pollination as well as the spraying needs of plant for fungicides insecticides which hurts bees. Last year thrips were a bigger issue for plants; you deal with insects on a year-by-year basis.

 

8.     What management practices, if any, have you taken to combat these issues?

Commercial growing has seen shrinking windows. Breeders are now coming out with hot set beans and corn for example. Next season green beans aren’t able for harvest until after Easter, used to be till May 5th. Yields are declining due to insect pests plus disease, increasing input cost becoming too high and not profitable. Shifting growing seasons have seen now it's even warm enough for pickling cucumbers in winter (used to be summer crop). 

 

9.     What management practices can other farmers of South Florida take to grow in changing climates? 

With using insecticide and fungicides it’s important to not irritate bees. Don’t apply sulfur for powdery mildew in squash before blooming and after bloom only use biological controls (i.e Bt spray) for worms. Wait till you see these pests and then spray to lower pressure of diseases without cold fronts which used to help decrease diseases and pests.

 

10.  What is your opinion on the future of growing vegetable crops in South Florida regarding changing climates and pollination?

Suggestion is to grow own bees if you are a vegetable farmer. From decreasing wild bee populations, home development, and urbanization farmers used to use 1 hive per acre now two hive per acres are needed. They have seen with watermelon production that bumblebees don't work for about 25% of blooms and they need 2 hives per acre now. Squash needs 1.5 hive per acre, and they work with own beekeeper. Beekeepers control mites in spring however they transport the bees, and travel leads to mites, as well as surrounding nurseries spraying insecticides causing farm bees to die. They also have serious issues with vandalism and theft. They keep bees in shaded areas under shade cloth and supply a solution water in trays around hives.

 

Post-Experiment Follow Up Survey

 

  1. What retailers do you mainly sell to? 

The major grocery stores we sell to in the United States are Publix, Ingles, Aldi‘s, and Kroger.

 

  1. How many acres of vegetables do you currently farm? 

Annually 1600 to 2000 acres.

 

  1. How many managed hives do you place per acre for squash (typical/current)? 

One to 1.5 hives.

  1. Which insecticides or fungicides did you apply / timing of spraying (before/during/after bloom). 

Too numerous to list, but prior to bloom we use what is necessary to keep the thrips at a minimum. Then in bloom we switch to soft chemistry, many organic products used in South Florida. We have every insect known to man living here.

 

  1. Roughly when did you first notice the production window shifting- approximate historical vs current planting/harvest months (e.g., used to be Oct–May, now Nov–Apr)? 

When the climate became warmer from 2010 to the present, we will see if growers change their windows north of us because of this cold winter.

 

  1. Do you track squash yield- can you share the flower strip season’s number or a before/after estimate?

 I have no data on the yields the only figures we keep our annual figures but the packout numbers have been higher. 

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