Irish Potato Famine
Prior to the 19th century, Ireland's farmers primarily grew grains such as wheat, oats, and barley. However, by the 1800s, due to a rapidly growing rural population, the Irish began to rely on just one crop – the “Irish Lumper,” a variety of white potato (Solanum tuberosum). It was easy to grow on small farms, even in the worst soil, and provided enough sustenance for impoverished tenant farmers and their families. In the mid-1840s a blight struck potato plants all over Ireland. Leaves would wither with shocking speed and when the tubers were dug up for harvest, they were found to be shrunken, mushy, and inedible.
Known as the “Great Hunger,” by 1851 one million Irish had died of starvation with another million emigrating to other countries, reducing Ireland's population of 8 million by twenty-five percent. With a current population of about five million, it has not recovered to this day. The huge flood of Irish pouring into the United States in the late 1840s had a profound effect on our country, especially in urban areas. By 1850 it was estimated one-quarter of New York City's population was Irish.
Cause of the Late Blight
Late blight affects a wide range of plants, including potatoes, tomatoes, peppers, and eggplant. Symptoms include brown-purplish spots and lesions on leaves and stems, with white fuzzy growth underneath the leaves, ultimately causing fruit rot and plant death. Late blight continues to be a destructive disease, causing serious agriculture losses worldwide in tomatoes and potatoes.
Late Blight Management
If you suspect your garden potatoes are infected by late blight, bring in a sample to your local UC Cooperative Extension office. You can also learn more about late blight at: https://ipm.ucanr.edu/PMG/GARDEN/VEGES/DISEASES/lateblight.html
Saint Patrick's Day
Denise Godbout-Avant has been a UCCE Master Gardener with Stanislaus County since 2020.
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By Cindy Watter, UC Master Gardener of Napa County
The Solanaceae, or nightshade family, is a large one. Just as our own families can include the kindly grandma as well as the femme fatale, nightshade plants embrace favorite edibles such as potatoes, peppers, eggplants and tomatoes, while also claiming toxic plants such as tobacco, brugmansia, belladonna and jimson weed.
The. 2,700 Solanaceae species have diverse habits, but they all produce solanine, an alkaloid toxin. In most foods, the solanine is present in such small quantity that it is harmless.
Let us dispose of the second, more sinister, group first. These plants are attractive in the landscape and useful in attracting pollinators, but you don't want to eat them. None of these toxic plants tastes good, so you would have to have a powerful thrill-seeking urge to consume them.
Even so, emergency rooms are familiar with jimson weed patients, who find the hallucinogenic plant in the wild. These unfortunate folks usually live to learn their lesson: leave foraging to the experts.
The name "nightshade" sounds dramatic, but some believe that the term arose because some nightshade flowers are particularly fragrant at night and some of the plants don't mind the shade.
The other nightshades, the edibles, are easy to grow. The tomato (Solanum lycopersicum), brought to Europe from Mexico, was initially considered inedible because of its relationship to the deadly nightshade. When people finally realized that tomatoes were safe and tasty and not just ornamental, cultivation took off, and the tomato became synonymous with Mediterranean cooking. Most of the solanine is in the leaves and stems anyway. The tomato is botanically a fruit: it develops from a fertilized flower and has seeds inside.
Tomatoes can be grown from seed, but it is easier to buy starts. Keep seedlings indoors until at least April. If the weather remains cold, you might have to wait until May or even June to plant them. The soil should be at least 60°F where you intend to plant, and the area should get lots of sun. All-day sun is ideal.
Plant seedlings deeply, so the lowest leaves are just above the soil surface. Rootlets will shoot out from the stem and form a strong base. This rooting also increases the plant's access to water and nutrients. If your soil contains a lot of compost, you will not need other amendments, although aged chicken manure and nitrogen are sometimes helpful.
Water your newly planted tomato seedlings deeply and keep the roots moist. Install supports, such as a cage, stake or trellis, when you plant to avoid disturbing the roots later. A support will keep the vine from sprawling on the ground and possibly rotting.
You can control most tomato problems, apart from gophers, by regular watering. Occasionally you may spot a large green caterpillar on the stems or leaves. That creature is a hornworm; remove it by hand.
Tomato growers enjoy friendly competition, and they love to share tips. One tip I learned last year is that gently shaking the plant when it's flowering will help spread the pollen from the stamen to the pistil, thus improving pollination and fruiting.
Bell peppers (Capsicum annuum) are a sweet pepper that can be eaten when it's underripe, or green. However, a fully ripe red pepper contains more nutrients, with more vitamin C than an orange. Wait to plant pepper seedlings outdoors until nighttime temperatures are above 55°F.
Peppers do well in containers, or you can space them 1-1/2 to 2 feet apart in rows. The warmer the weather during the growing season, the more flavorful the peppers will be. You can use row covers to keep pests out; organic bait will control slugs and snails. However, the least toxic snail bait is a jar lid full of beer. The slugs drown in it.
Eggplant (Solanum melogena) is a particularly beautiful plant. Like the tomato and the pepper, the eggplant is a fruit. Its flowers are lilac colored, and its leaves are dark green. I have seen eggplants used to great effect as part of a landscape treatment. Again, resist setting out seedlings until frost season is over. They like warm weather. Plant them three feet apart.
You can grow lots of small eggplants, or you can pinch off some flowers to encourage larger fruits. The eggplant benefits from fertilizer such as aged chicken manure or worm castings.
I sometimes wonder what the Europeans ate before they raided Montezuma's garden. The potato (Solanum tuberosum) is a staple of the European diet, yet it originated in the Andes.
To grow potatoes, cut chunks from a seed potato, making sure there is an "eye" (sprout) on each chunk. Supermarket potatoes may have been treated with a sprouting inhibitor, so it's best to start with real seed potatoes from a nursery.
As soon as you can put a shovel in the soil, you can plant potatoes. Plant them in rows in loose soil amended with plenty of compost. If you use fertilizer, don't let it touch the potatoes.
Pile a few inches of loose dirt above the seed potato. Leafy stems will emerge. When the greens are eight inches tall, bury all but four inches in loose soil, straw or shredded leaves. This process, known as hilling, creates more room for new potatoes to develop. Keep building the mound as the potato leaves grow, leaving about four inches of greens exposed. When the vines flower, you can stop hilling. Potatoes need to grow in darkness, so if the ground is disturbed and you see a potato, cover it up. Light will turn the potato green, and the green part is toxic.
The nightshade family produces some of our favorite garden edibles. Colorful tomatoes, peppers and eggplants are beautiful as well as useful. As for potatoes, it's fun to dig them out of their little hills, which add variety to your vegetable bed.
Food Growing Forum: Second Sunday of the month through November. Sunday, April 11, 3 pm to 4 pm: “Tomatoes, Peppers and Eggplants.” Register to get Zoom link: https://bit.ly/3lC3qs8
Workshop: UC Master Gardeners will lead a workshop on “Growing Tasty Tomatoes” on Saturday, March 27, from 10 a.m. to noon.” Register to get Zoom link:
Napa Library Talks: First Thursday of each month. Thursday, April 1: “Gardening on a Shoestring.” Register to get Zoom link: https://bit.ly/3rn3MF3
Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to mastergardeners@countyofnapa.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email.
For more information visit http://napamg.ucanr.edu or find us on Facebook or Instagram, UC Master Gardeners of Napa County.
![Nightshade vegetables. (naturalhealthtechniques.com) Nightshade vegetables. (naturalhealthtechniques.com)](/blogs/blogcore/blogfiles/78905.jpg)
![Jimson weed. All members of the Datura genus are toxic. (natureid.blogspot.com) Jimson weed. All members of the Datura genus are toxic. (natureid.blogspot.com)](/blogs/blogcore/blogfiles/78906.jpg)
![Tomatoes. (borntogrow.net) Tomatoes. (borntogrow.net)](/blogs/blogcore/blogfiles/78907.jpg)
![Soil should be 60 F before planting tomatoes. (cooper-atkins.com) Soil should be 60 F before planting tomatoes. (cooper-atkins.com)](/blogs/blogcore/blogfiles/78908.jpg)
![Solanaceae love all-day sun. (designtrends.com) Solanaceae love all-day sun. (designtrends.com)](/blogs/blogcore/blogfiles/78909.jpg)
![Plant tomatoes deeply--they grow more roots. (UCANR.edu) Plant tomatoes deeply--they grow more roots. (UCANR.edu)](/blogs/blogcore/blogfiles/78910.jpg)
![Provide tomatoes with support. (homestead-and-survival.com) Provide tomatoes with support. (homestead-and-survival.com)](/blogs/blogcore/blogfiles/78911.jpg)
![Tomato hornworm, in case you haven't seen one. Looks fearsome, but just wants to eat tomatoes. (UCANR.edu) Tomato hornworm, in case you haven't seen one. Looks fearsome, but just wants to eat tomatoes. (UCANR.edu)](/blogs/blogcore/blogfiles/78912.jpg)
![Bell peppers. (snaped.fns.usda.gov) Bell peppers. (snaped.fns.usda.gov)](/blogs/blogcore/blogfiles/78914.jpg)
![Plant peppers when night temps are reliably over 55 F. (maudesport.com) Plant peppers when night temps are reliably over 55 F. (maudesport.com)](/blogs/blogcore/blogfiles/78915.jpg)
![Protection, if needed. (almanac.com) Protection, if needed. (almanac.com)](/blogs/blogcore/blogfiles/78916.jpg)
![Eggplant flowers. (cultivatetoplate.com) Eggplant flowers. (cultivatetoplate.com)](/blogs/blogcore/blogfiles/78917.jpg)
![Potatoes are also in the family. (jessicagavin.com) Potatoes are also in the family. (jessicagavin.com)](/blogs/blogcore/blogfiles/78918.jpg)
![Hilling potatoes. (veggiegardener.com) Hilling potatoes. (veggiegardener.com)](/blogs/blogcore/blogfiles/78919.jpg)
![Solanaceae family characteristics. (slideshare.net) Solanaceae family characteristics. (slideshare.net)](/blogs/blogcore/blogfiles/78920.jpg)
- Author: Megan McCaghey, mmmccaghey@ucdavis.edu
- Author: Cassandra Swett
Southern blight, caused by the fungus Sclerotium rolfsii, is a soilborne pathogen that is increasingly becoming problematic in many crops - including tomato, potato, sunflower, bean, and pepper - likely due to higher spring and summer temperatures. Initial symptoms of southern blight include a yellowing of the foliage with slight darkening of the stem just above the soil line. Lesions on the stem at or near the soil line develop rapidly, girdling the stem and causing sudden and permanent wilt of the plant. The fungus grows downward on the stem, rotting the cortical tissue. White mats of mycelium develop on the stem and nearby soil. In a few days, tan to brown spherical sclerotia (tiny compact masses of hardened, fungal mycelium) may appear on the mycelial mat. The sclerotia are a good diagnostic feature of this disease in many crops, but are rare in some, like tomato.
Infections by S. rolfsii are triggered by warm temperatures and moist soil conditions. The inconsistent development of southern blight from year to year makes it hard to determine when or if fungicides might be needed in a given year. To address this problem, we are developing a risk forecasting tool which can alert growers to southern blight risk events in the growing season, to inform when fungicide applications are required to control the disease. This summer, we are collecting data on soil temperature, soil moisture, and disease incidence in annual cropping systems throughout the Central Valley to develop a predictive model, which we are validating in controlled trials in collaboration with UCCE advisors Brenna Aegerter and Jaspreet Sidhu. While fungicides can effectively control southern blight, dense canopies and a lack of crop registrations limit their usefulness; moreover, there are limited fungicide options available to organic producers, who are often the most impacted by this disease.
A second goal of our project is to provide an integrated management toolkit for southern blight, which includes organic options. This involves generating information on better or worse crop rotations in southern blight infested fields, continuing work we started with UCCE advisors Amber Vinchesi-Vahl and Sarah Light in 2018. We are examining changes in fungal densities in soil following planting to various crops over three years (2018, 2020, 2021). We're also exploring pathogen-suppression using: 1) chitin amendment to stimulate microbes that break down chitin, and in turn the chitin-based survival structure of S. rolfsii, and 2) soil solarization in the fall to kill the pathogen in the soil.
The deliverables from this project will include a disease forecasting tool, information on crops that are severely affected by the disease and increase southern blight loads in fields (to avoid) and crops that are less affected and do not increase southern blight loads (to rotate with more susceptible crops), as well as soil treatment strategies for infested fields.
This project is supported by the USDA NIFA Postdoctoral Fellowship and the California Potato Board. Collaborators include Brenna Aegerter, Rachael Long, Mrinalini Narayan, Neil McRoberts, Kelley Paugh, Jaspreet Sidhu, Amber Vinchesi-Vahl, UCCE Colusa County, and the UC Davis Department of Plant Pathology. For more information, contact Cassandra Swett at clswett@ucdavis.edu.
- Author: Karey Windbiel-Rojas
They are Jerusalem crickets, also sometimes called sand cricket, niña de la tierra (child of the earth), potato bug, and stone cricket.
Jerusalem crickets are relatives of crickets, grasshoppers, and katydids. These large insects can be up to two inches long and have heads that somewhat resemble a human head. Their head and body are amber colored, with dark stripes on the abdomen, long antennae, and no wings. Their thick legs are designed for burrowing in the ground.
Jerusalem crickets generally feed on other insects and sometimes on tubers (like potatoes). They have powerful jaws and can bite humans, but they are not poisonous. The bite can be painful, so be careful when handling.
If you find one in your garden, don't worry; Jerusalem crickets do not usually build up in high numbers and cause little if any damage to plants. Learn more at http://ipm.ucanr.edu/PMG/GARDEN/VEGES/PESTS/jeruscricket.html
- Author: Roberta Barton
Discolored leaves. Decaying roots. Dead wood. Mother Nature offers a fascinating and colorful backdrop of clues to track microscopic killers. Much like any medical mystery, experts are called in to diagnose or identify a disease from its symptoms and recommend management strategies to prevent further damage or loss of healthy plants.
In the world of crop science mysteries, plant pathology solves the crime. The usual suspects include bacteria, fungi and viruses.
Humans and animals depend on plants for their food supply and ultimately for their survival. When diseases threaten crops, a high-quality, affordable food supply is placed at risk. For growers, plant diseases can reduce crop yields. For consumers, reduced crop yields can drive higher food prices. Plant pathology research holds enormous implications for a sustainable food supply.
Florent Trouillas, who was named UC Cooperative Extension specialist in the Department of Plant Pathology at UC Davis and the Kearney Agricultural Research and Extension Center last year, explains the bottom line of most concern to growers.
"Once we identify a disease causal agent, a main question remains from growers. What growers really want to know is how to control the disease and prevent its spread to new healthy plants; they look to the University of California for solutions," Trouillas said.
A crisis in the food production system can impact other areas of society as well. In fact, history is filled with examples of how plant diseases influenced economies, environments and human societies.
Another historical illustration of plant pathology research occurred in the 1920s. The most common trees in the forests of the United States at the turn of the century were the majestic American chestnuts. The trees generated income for humans and the timber industry, served as a food source for people and animals, and provided habitat for wildlife. Then the trees started dying, until by the late 1920s, they had become the first tree in modern times on the brink of extinction. Plant pathologists were particularly adept at identifying plant diseases by this time and diagnosed the Cryphonectria parasitica fungus as the cause of the chestnut blight. By preventing the extinction of the pivotal species, plant pathology had a direct impact on the economy and the environment.
More recent major plant disease outbreaks in the United States involving plant pathology research have included Sudden Oak Death with devastating effects in California and Oregon forests, pitch canker killing California native pine species, and citrus canker in Florida, which has had a huge economic impact on the industry.
Veterinarians treat diseases in animals, physicians in humans. Trouillas describes the role of plant pathologists in similar terms. “We study the pathology of plant systems. Plant pathologists treat plants," he said.
Healthy plants ensure a sustainable food source and habitat for so many other organisms, including the human species.