Update #5—My observation research coming to an end

Since my last update, my research has slowed down and I am finishing up final pieces of data collection. Within the past two weeks, many more plants have died and also succumbed to disease. In total, 43 out of the original 72 have died—primarily the plants that border the soccer field and the back hill field space, while the plants in the center of the plot seem to have been “buffered.” During my last observation trial, the majority of plants did not produce female flowers and had greatly reduced numbers of male flowers when compared to the beginning two trials. Because of this, my third observation trial that ended on August 3rd was my last trial. There is simply too much damage to the plants that there are very few pollinators to observe. 

 

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Notice how most pots had “none” under recorded female flowers

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Earlier in research when there were many female flowers per pot

 

The primary cause of all this death is the cucumber beetles, which I expected to be the cause of my research’s demise. However, I did not expect the sudden spread of downy mildew that turned a lot of the leaves yellow, and resulted in root rot. The variety that I have planted, Marketmore 97, is advertised as downy-mildew resistant. Throughout the experiment, I have seen a few leaves with mildew spots, but have been able to cut them off and the plant remained unaffected. I expected downy mildew in part because it is not specific to cucumber plants, and can infect many others. Since my plot is located next to a large vegetable garden, I expected downy mildew to eventually reach my plants too. After doing some research this week, I found that diseases such as downy mildew (and other bacterial and fungal diseases that appear similarly) can be spread through cucumber beetles. 

 

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Yellowing leaves due to downy mildew

Ultimately, the scale of the cucumber beetles was far too big for me to handle organically. However, it is more important that I do not use inorganic pesticides that would be the most detrimental to my project and render my data useless. While it is frustrating to see all of my hard work and time to be destroyed by beetles in a few days, I know that at this point it is out of my control and I have done everything possible to minimize the beetle damage and prolong the experiment. Additionally, after speaking with local farmers, I have realized that I was not the only one battling the beetles this summer. Two other farmers located in central MA noted  that the cucumber beetles have been especially bad this year and a lot of their crop has died. Last year the biggest pest was another type of beetle that feasted on beans. It was just by chance that this year gave perfect conditions for cucumber beetle growth.

At this point, I am maintaining the plants that are left and continuing to pick off the beetles. I am still gathering data on the fruit that was set during the observation days. I have picked the cucumbers that resulted from the flowers that were open during the first trial (July 17th-20th). I continue to take data on the cucumbers at 10 days after flower opening and then I harvest at the 20 day mark. While on the vine, I just take general notes on coloring and shape, and measure the length. Once I harvest, I will take the length, circumference at different points, volume, weight, and also make several slices into the cucumber to see how many ovules have been fertilized (seed present) vs. unfertilized at a given section of the fruit. More to come on the fruit data collection process and findings!

 

Comments

  1. cmahlbacher says:

    That is too bad about the beetles and mildew. I understand why using pesticides is an unattractive option to combat these forces. What are the organic alternatives for keeping beetles and mildew away? Can they be as effective as the inorganic methods?

  2. Good question. The organic alternatives are mostly soaps that harm potentially other insects that could pollinate, so I could not use these either. I did, however, use a mild soap mixed with cayenne pepper and put this in the soil to deter the beetles from laying eggs in the soil. Unfortunately, organics are just not as effective or powerful as the inorganics.

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