Fruit and Vegetable News

Author: Shane Bugeja, Local Extension Educator, Blue Earth and Le Sueur counties with edits and review from Natalie Hoidal & Carl Rosen With the advent of soil and foliar testing, we can analyze dozens of specific nutrients and tailor applications of fertilizer to each field and crop. With this wealth of information, several philosophies about how best to feed the soil have emerged. These include the “sufficiency/feed the plant” and the “build and maintain” methods, where the amount of fertilizer is determined by maximum profit or lowest risk, respectively. However, one alternative approach deals with soil nutrient ratios rather than pounds per acre. Intro to the Albrecht Method Ratio-based fertility programs first emerged from potassium research in the 1930’s and 40’s in New Jersey. The agronomists there noticed that the highest quality alfalfa plants tended to have similar Ca/Mg/K ratios within their leaves and stem. They then extrapolated that an “ideal soil” must also h...

Author: Natalie Hoidal, UMN Extension We've seen some very heavy rains followed by hot weather over the last couple of weeks. These conditions can cause crusting on the soil surface. In this brief overview, I'll discuss how / why crusts form, and how you can respond in the immediate and longer term. At this point in the season, most crops are already in the field. However, many of you will continue to plant successions of brassicas, lettuce, carrots, and other crops. We tend to see some of our heaviest rains and thunderstorms in the summer, so keep the possibility of crusting in mind as you time your plantings. Soil crusting: Why does it happen?  Crusting often leads to uneven emergence Photo: Angie Peltier Soils that have high aggregate stability (a function of soil texture, organic matter, and biological activity) are able to retain their structure in the face of heavy rainfall. A soil with lower aggregate stability is more likely to experience some disintegration...

Author: Natalie Hoidal, UMN Extension Educator for local foods and vegetable production Spring temperatures have been cool across the state, and some of you may be holding onto your transplants longer than usual. In Minnesota this May, we’ve accumulated anywhere from 35 to 75 fewer growing degree days than what we would see in an average May. There are a few things you can do to slow down transplant growth prior to transplanting, and to reduce transplant shock: Before transplanting Limit growth if you need to hold transplants longer than expected If your plants are starting to stretch and you’re not ready to transplant into the field, there are a few ways you can reduce growth and stem elongation. By lowering the overall temperature of your greenhouse or high tunnel, plant growth will slow down. This may also help to harden off your plants and reduce transplant shock. Another option is to simply bring your plants outside during the day if doing so is feasible with the scale...

Author: Natalie Hoidal, UMN Extension Educator, Local Foods and Vegetable Production With so many types of available soil tests available, how do you know which analyses to select, and how often should you do each one? As of the publishing of this article, the University of Minnesota Soils Lab is still processing samples. Due to COVID-19 precautions, they cannot accept in-person drop-offs, and all samples must be submitted through the mail. Due to reduced staffing, your sample may be delayed.  Soil test forms have many options, it can be difficult to know which tests you need.  There are a few nutrients and soil properties that can be measured reliably with a soil test, and should be done every 2-3 years. Organic Matter Organic matter is a good basic measure of soil health and is a reservoir of nutrients essential for plant growth. This test should be done every few years when organic matter levels are optimal. If your organic matter is low, consider a soil tes...

Author: Natalie Hoidal, UMN Extension horticulture educator We're seeing some cases of low fruit set and / or fruit abortion in pumpkins and winter squash. If this is happening on your farm, there are a couple of potential explanations: 1. Pollination Pumpkins and squash are dependent upon insect pollination. Male flowers bloom about a week before female flowers, and flowers only bloom for a few hours in the morning, so it's crucial that conditions are right for pollination. Penn State Extension has an excellent, in-depth article on pollinators in pumpkins and squash . Some of the highlights include:  Bumblebees and squash bees ( Peponapis pruinosa)  are the best pollinators of pumpkins since they forage in the morning, and because squash bees have a lifecyle that's perfectly timed with the lifecycles of cucurbits. Cucurbits include pumpkin, squash, melons, cucumbers, and zucchini.  Creating habitat on your farm for nesting sites may help boost pollination ...

Authors: Bill Hutchison, Eric Burkness, Lu Yin, and Matt Clark. The foliar form of Grape Phylloxera (GP) is quite common throughout Minnesota and most eastern grape growing regions of the U.S. Although we have experienced a late spring so far this year, the first grape leaves for most hybrids have started to appear; this is a good time to begin monitoring for the “yellow crawler” stage of GP, as the crawlers hatch from their “mother” galls (including a female with several eggs, Fig. 1). Grape Phylloxera Life Cycle In brief, the GP life cycle is quite complex, with galls formed on both root and foliar portions of the vine. However, given the genetic background of the cold-hardy grape hybrids in the Midwest region, the primary potential for damage is the presence of foliar galls formed by GP. Much of this information is taken from a recent publication by one of our graduate students in Horticultural Science, Lu Yin (Yin et al. 2019; see full citation below). Fig. 1. Mature grape ph...

Author: Matthew Gullickson . In late summer, just as fall-bearing raspberries are starting to ripen, researchers from the University of Minnesota West Central Research and Outreach Center (WCROC) are attempting to protect the berry crop from destruction. Their main concern is to protect the fruit from a recently established invasive insect pest, spotted-wing drosophila (SWD), which feeds on many kinds of soft fruit including raspberries.  A male Spotted-wing drosophila fly with distinctive wing markings. Photo: UMN FruitEdge SWD began appearing in Minnesota in 2012. Since its arrival, this pest has been responsible for significant damage to berries with major economic losses in Minnesota and nationwide. Adult SWD lay eggs in ripening fruit, which later hatch and feed on the flesh of the fruit, which results in unmarketable, mushy fruit with unwanted maggots inside at the time of harvest. SWD populations grow quickly; it takes just over a week to develop from egg to adult, and...

Author: Laise Sousa Moreira. If you are like many Americans, you love grapes. Table grapes are the third most consumed fruit in the U.S., but growing this delicious fruit is a real challenge in regions with extremely low temperatures. Seedless table grapes. Photo: Laise Moreira. Minnesota has a harsh winter and short growing season which creates obstacles for growers to produce grapes year after year or if any at all. Currently, most of the seedless cultivars available in the market were developed for warm climates, dry conditions, or mild winters, which is not the case for the climate here in Minnesota. There are a few cultivars that are being tested here in Minnesota at the University of Minnesota Horticultural Research Center. Many of these come with restrictions such as burying vines in the ground every year before the winter because these cultivars are not hardy enough to survive the extremely low temperatures during dormancy (time while the plant is not growing). Thus, se...