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

115 articles by this author

Article List
Grape: Full veraison on most varieties

Apple harvest has begun with early varieties still being harvested. A lack of cool nights has delayed red color development but many varieties are still developing acceptable red color. Quality generally looks good.  


PristineTM apple

Although PristineTM was selected in 1982, its history goes back to the early days of the PRI breeding program. From an original cross of Rome Beauty with Malus floribunda 821, selections and hybridizations were made incorporating Golden Delicious, McIntosh, Starking Delicious  and Cazumat along the way. The cross that resulted in PristineTM was Coop 10 x Cazumat made in 1974 at Rutgers University in New Jersey, and PristineTM was selected at the Purdue Hort. Farm in 1982. PristineTM is a very early maturing apple usually ripening in late July in Lafayette. In most seasons it will be a couple of weeks ahead of Gala. It is very attractive with a clean finish. For such an early apple, it has very good eating quality, certainly much better than other very early apples such as Lodi or Transparent. The texture is crisp and flavor has a good acid/sugar balance. If fruit are[Read More…]


ReTain (AVG) is a plant growth regulator that blocks the production of ethylene. When ReTain is applied to apple, several ripening processes are slowed, including preharvest drop, fruit flesh softening, starch disappearance, and red color formation. In order for ReTain to be effective it must be applied well in advance of the climacteric rise in ethylene production that signals the onset of fruit maturity. If applied too early the effects may wear off prematurely. If applied too late, a significant portion of the crop may not be responsive to AVG, having already begun to produce autocatalytic ethylene. A second reason for avoiding late applications of ReTain is the 21 day preharvest interval (PHI), which, combined with a late spray date could result in an undesirable delay in harvest. The label recommends applying ReTain four weeks before anticipated harvest (WBH). This has sometimes caused confusion, as the grower is timing the[Read More…]


Preharvest drop refers to the process where fruit fall from the tree prior to harvest. Not all apple varieties are affected, but with some, such as McIntosh and Pristine, pre-harvest drop can be extreme. Several growth regulator materials are available to growers to help reduce pre-harvest drop. These materials are often referred to as “stop-drop” or “sticker” sprays. The traditional material used to help prevent pre-harvest drop on apples is NAA (Fruitone N), a synthetic auxin. Other synthetic auxins you may have heard of include 2,4-D and 2,4,5-T.  Of course you also know Fruitone N as a chemical thinner.  Early in the season NAA knocks fruit off the tree and later towards harvest it sticks them on.  This highlights the importance of timing when using plant growth regulators. Another newer stop drop material is ReTain (see articles by Schupp and Schwallier in this issue). Although both NAA and ReTain can[Read More…]


grapes turning color

Early grapes are just beginning to soften and color (veraison). Summer raspberry harvest if winding down and fall bearing types are flowering. Blueberry harvest continues. Japanese beetle numbers continue to be relatively high in the Lafayette area. Peach harvest (for those fortunate to have a crop) has begun. Early apple cultivars are approaching harvest.


Figure 1. Staining of starch of apple fruit by misting with iodine solution. Fruit 0-2 are unripe with much starch remaining. At ratings of 5-6, most of the starch has disappeared (converted to soluble sugars) and are ready for harvest

Making the decision on when to harvest can be a very tricky and complicated issue. The longer you intend to store the fruit, the more precise your timing needs to be.  For summer apples, most growers only intend to store fruit until their higher quality fall apples come on stream, so storage times beyond a week or two are not that common.  For example, very early season apples such as Lodi and Pristine should only be stored for a few weeks until Gala harvest begins. Even for fall apples, many Indiana growers aim to sell the majority of their crop immediately to the consumer, and try to be done by mid November or so. Since storage times are relatively short, harvest maturity is less important than for longer term storage.  This being the case, apples should be harvested when they are fully ripe.  This will maximize their flavor, and although[Read More…]



Garwood Orchard

Thanks to all members of the Garwood family and staff who hosted us for the summer field day last week. Growers were inspired by the excellent job Garwoods do with fruit and vegetable production and marketing. The fruit, vegetable and farm marketing industries in the state were well represented, and all in attendance appreciated members of the Garwood family sharing their many successes and a few challenges along the way. Thanks to Brian and all members of the Garwood family and staff for their hospitality. Sincerely, Peter Hirst  


  Following the success of last year’s Summer Field Tour at Tuttle Orchards, this year we are again planning a combined summer field tour with the Indiana Horticultural Society, the Indiana Vegetable Growers’ Association and the Indiana Farm Market Association. We will be hosted by Garwood Orchards in La Porte, IN. While we encourage membership in these industry organizations, all those who are interested are welcome and invited to attend, regardless of membership status. Garwood Orchards is one of the largest and best managed orchards in the state. It may seem puzzling that they can manage such a large operation and manage it so well. That’s why we’re visiting – to not only be inspired but learn a few of their tricks and see how they do it. They have aggressively planted new cultivars and crops and have been on the forefront of adopting new technologies. They are major producers[Read More…]


The warm weather is pushing crop develop rapidly. Grapes are at bunch closure, summer red and black raspberry harvest has begun. Some primocane fruiting types are beginning to flower. Gooseberry and currant harvest has begun. Apples are 1-2 inches in diameter. Strawberry harvest is over and renovation has begun. The chemical thinning window has closed and hand thinning is underway. Growers should hand thin the most biennial cultivars first. Japanese beetles are plentiful!