Peter M Hirst

Facts for Fancy Fruit Editor & Professor of Horticulture
Department of Horticulture and Landscape Architecture
Area(s) of Interest: Commercial Tree Fruit Production

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For organisms that don’t regulate their temperature (such as plants and insects), the rate of development is largely controlled by the temperature of their environment. As we know, fruit trees and vines need a certain amount of “winter chilling” that they use to measure when winter is over. After the chilling period, plant development depends on temperature. Fruit plants in Indiana are primed and ready to grow – right now they are just waiting for suitable temperatures. Waiting, and waiting and waiting. Typically very little plant development occurs below 50F so we measure heat accumulation above 50F (Growing Degree Days) to predict the rate of plant development.  As we see from Figure 1, this year (solid black line) in Lafayette we have accumulated very few GDD, and those derived from a few warm days at the end of February. We have not accumulated any GDD since March 1, but with[Read More…]



A new Monsanto-backed company is on the verge of producing the first fruit made with a blockbuster gene-editing tool that could revolutionize agriculture In a move aimed at securing its future, Monsanto has invested $125 million in a gene-editing startup called Pairwise. The alliance could tee up Monsanto, long known for its controversial dealings with farmers and its role in popularizing genetically modified organisms, to introduce some of the first produce made using the blockbuster gene-editing tool Crispr. In a call with Business Insider, the company hinted that strawberries or another type of fruit would be among the first Crispr produce to hit grocery-store shelves — a development it expects within five to 10 years. In a move aimed at securing a place in the rapidly evolving food technology scene, the agricultural giant Monsanto has invested $125 million in a gene-editing startup called Pairwise. The alliance could tee up Monsanto,[Read More…]


The New York Times reports China has proposed countermeasures to a proposed $60 billion in tariffs from the U.S. on Chinese-made products. The Chinese Ministry of Commerce issued the threat in an online statement. American goods including nuts, wine, and fresh fruit would be subject to 15% tariffs. The Times reports these proposed tariffs in total will impact just about 2% of all U.S. exports to China, which amount to $130 billion. “It’s not devastating economically by any stretch, but it’s certainly going to hurt those interests in the United States that are trying to export,” Chad Bown, a senior fellow at the Peterson Institute for International Economics, told the Times. He pointed out that the retaliation by China sends “a negative signal that they are not seeking to de-escalate things.   Reaction from Industry Members: Almond Board of California President and CEO, Richard Waycott says market access is critical[Read More…]


Of course, we all hope for a late spring to help avoid the risk of damage from late spring frosts. But when the temperature warms up then turns cold again, it leaves us in a real bind. The warm temperatures push tree development, then we want the warmer conditions for good pollinating weather. When we have open flowers but conditions not favorable for high bee activity (cool or very windy conditions), there is a risk of poor pollination and fruit set. Not only do these cool conditions limit bee activity, they result in poor growth of pollen tubes even if bees do successfully pollinate flowers. Daily temperatures of 60F or above are required for good pollen tube growth, so if there are open flowers and the temperatures have consistently been cooler than 60F, you could be in trouble. There is some evidence that apples tend to set mostly on king[Read More…]


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So far it has been a cool spring, that in the northern half of the state has helped hold back bud development. As we can see from Figure 1, in Lafayette we have only accumulated 25 growing Degree Days (GDD), and most of these were the result of two warm days (54 and 63 F) in late February. Since then we have not accumulated any more GDD, so plants have mostly not begun to show any signs of growth. This has brought the timing of growth back into line with the last few years. Note that since 2010, every year has been earlier than the long-term average (“normal” in Fig. 1).  


Blackberry dormant

It has been a cool spring so far and most fruit crops are still relatively dormant in the Lafayette area. Early grapes are just at bud swell, red raspberries are also showing signs of growth, sweet cherry buds are swelling, and early apples are at silver tip. Fruit trees in Lafayette remain dormant, however are pushing forward in more southern areas of the state. In southern Indiana apples are at or past full bloom and peaches are in shuck split. Blackberries are at half-inch green.


May 7, 2018 Purdue Wine Grape Team “From Grape to Glass” Byler Lane Winery 5858 County Road 35, Auburn, IN 46706 Contact Jill Blume blume@purdue.edu June 26, 2018 Indiana Hort Society Summer Field Day Garwood Orchard, LaPorte, IN Contact Lori Jolly-Brown ljollybr@ purdue.edu October 17, 2018 Indiana Flower Growers Conference Daniel Turf Center Contact Lori Jolly-Brown ljollybr@ purdue.edu January 8, 2019 Illiana Vegetable Growers Symposium. Teibel’s Family Restaurant, Schererville, IN Contact Liz Maynard emaynard@purdue.edu https://ag.purdue.edu/hla/Extension/Pages/IVGS.aspx February 12-14, 2019 Indiana Hort Congress. Indianapolis Marriott East Indianapolis, IN Contact Lori Jolly-Brown, ljollybr@purdue.edu or 765-494-1296 http://www.inhortcongress.org  



Apple harvest is winding down with late varieties such as GoldRush and Pink Lady being harvested. Quality has continued to be good, although some stem-end cracking has shown up on some cultivars. We have continued to run about a week early throughout the season.