March 10, 2022

Tips in Preparation of Herbicide Shortages in 2022 – Tree Fruit and Small Fruit Crops

Thierry E. Besançon, Rutgers University, and Lynn M. Sosnoskie, Cornell University

Many growers in the US have been focused on predicted herbicide shortages in the upcoming field season. While the primary concerns have surrounded glyphosate and glufosinate, there is increasing apprehension that active ingredients of importance to tree fruit and small fruit growers may also be affected. Although the supply change is dynamic, chemical stocks may become, and remain, tight at the local or regional level as growers try to fill gaps in their toolboxes. As spring residual herbicide are soon to be applied, please consider the following when planning for the 2022 season.

Important note: Not all herbicides are available in all crops in both New Jersey and New York. Always review current labels before applying products

 

Successful Weed Identification, Regular Scouting and Detailed Field Records are Crucial for Optimizing Weed Control Success

  • The first step in developing a novel herbicide program is knowing what species are present and determining which combination of products will be the most effective (and affordable) at suppressing them. Not all active ingredients are equally useful against all species and careful consideration needs to be paid to each chemical’s spectrum of control. Please, carefully review herbicide effectiveness tables for various weed species that are available in the 2022 Commercial New Jersey Pest Control Recommendations for blueberry, tree fruits or grape (https://njaes.rutgers.edu/pubs/). Similar tables are available in Cornell’s weed control guides (PMEP Guidelines (cornell.edu))

Familiarize Yourself with Chemical Substitutes before Applying Them over Many Acres

  • Some switches may be intuitive (e.g. using Poast (sethoxydim) or Fusilade (fluazifop) in place of clethodim where allowed) while others may be more complicated (e.g. using a tank-mixture in place of a single product). In addition to knowing a product’s target species, become acquainted with each herbicide’s labeled rate structure and spray volume, use patterns (e.g. application timing), environmental limitations (e.g. soil type or temperature restrictions), adjuvant requirements, and potential interactions with tank-mix partners. Not all chemicals are compatible with each other, and antagonism can reduce weed control efficacy while enhancing crop injury concerns. Contact your Extension Specialists if you have any doubt regarding physical compatibility and efficacy of herbicides mixtures.

Soil-Applied Preemergence Herbicides are Critical Tools

  • Soil-applied preemergence herbicides are very useful tools for suppressing weeds that emerge with the crop; these plants are the most injurious as early season competitors are very likely to reduce yields. Like postemergence products, soil-applied herbicides must be carefully selected to balance crop safety with weed control needs. Pay attention to rate requirements according to soil type, as this can influence both efficacy and injury. Preemergence herbicides need to be moved (aka activation) into the soil solution (via either rainfall or irrigation) where they are taken-up by emerging weed seedlings; delays in activation can reduce overall performance if some weeds continue to germinate and emerge under low soil moisture conditions. Delays may also facilitate the degradation of some products susceptible to breakdown in sunlight (i.e. photolysis). Be aware that trickle irrigation may cause less effective and less consistent weed control by washing off residual herbicides from top soil where weeds germinate, thus increasing herbicide application costs. When possible, use overlapping residual products to suppress weed emergence throughout the season. Some active ingredients may have both preemergence and postemergence activity (e.g. flumioxazin (Chateau) or simazine (Princep)).

Timing Matters

  • Postemergence (i.e. foliar) weed control should be undertaken when weeds are small and succulent. Herbicide labels will have specific recommendations regarding the optimal size for treatment. For instance, clethodim (Select Max) and sethoxydim (Poast) have a maximum height or lateral growth requirement of 6 inches for effective control of goosegrass or crabgrass. Weeds are more sensitive to control measures when they are small and succulent, so rapid identification and management will improve control success. Because many foliar-applied herbicides can also damage crops, as well, always follow label guidance to reduce risk of injury.

Optimize Herbicide Application Rate for Postemergence Applications

  • Target using the lowest effective herbicide rate to stretch your herbicide supply. For example, instead of applying 32 or 44 oz/acre of a glyphosate brand product, consider using the standard rate on the label such as 22 oz/acre for Roundup PowerMax. Again, timing of application with regards to weed size will be critical to optimize your herbicide supply. The smaller the weeds, the less herbicide you will have to apply to control it! Therefore, frequent scouting as highlighted above will be very important to optimize your herbicide application and stretch your herbicide supply.

Don’t Skimp on Adjuvants

  • If herbicides are going to be in short supply, then there may be fewer shots to control weeds. If there are fewer shots available, make every shot count as much as possible. Follow label recommendations regarding the inclusion of water conditioners, surfactants, etc…, to maximize product efficacy. Refer to point number two about potential compatibility concerns when tank-mix partners are involved.

Get Perennial Weeds under Control

  • Perennial species such as Canada thistle, goldenrods, bindweed or quackgrass are frequent and troublesome weeds of tree fruit and small fruit crops. Because control of these weeds requires the use of systemic herbicides that may be in short supply (i.e. glyphosate), appropriate timing of application will be critical to maximize herbicide efficacy. For example, Canada thistle should be sprayed with a systemic herbicide in late spring after flower buds started to develop whereas Virginia creeper or poison ivy should be targeted in mid- to late summer after vines flowers but before fall color appears in the foliage. Use effective alternatives such as clopyralid (Stinger) for control of leguminous and composite (e.g. Canada thistle) weeds or soil-applied pronamide (Kerb) for control of perennial grasses where authorized. This may help you to reserve the use of glyphosate for perennial weeds that cannot be efficiently controlled by other products.

Consider Non-Chemical Weed Control Strategies When and Where Appropriate

  • This includes hand weeding, cultivation, and mowing practices. Like herbicides, these practices are not effective against all species at all times. For example, while cultivation can control many weed seedlings, particularly at the white-thread stage, soil disturbance is less effective against well-developed plants. In the case of some perennials (for instance, field bindweed or Canada thistle), cultivation contributes to break up and disperse root fragments within and across fields, facilitating dispersal. Ultimately, plan for hand-weeding escapes prior to the weeds setting seeds as this will help reducing the weed seedbank for future growing seasons.

Plan Ahead Now!

  • 2022 could be a difficult year if many crop production and protection chemicals are limited. Herbicide shortages could impact weed control success in the coming growing season…and beyond. Weeds that are not controlled in 2022 will set seed that will cause problems in the future. Planning now can help with weed management in both the short and long term.
Filed Under: Blueberry, Cranberry, Fruit, Strawberry, Tree Fruit, Vegetable Crops, Wine Grape Tagged With: , , , , , , ,
February 17, 2022

Early Season Tree Fruit Pest Control for 2022

  • Dormant season oil sprays
  • Dormant season copper sprays
  • Dormant season urea sprays

[Read more…]

Filed Under: Tree Fruit Tagged With: , , , , , , ,
June 29, 2021

About the safe use of glufosinate and glyphosate herbicides in apple and peach orchards

Recently, New Jersey tree fruit growers have expressed concerns regarding the use of glufosinate for weed control in apple and peach orchards.

Glufosinate is a nonselective post-emergence foliar herbicide that can be used for directed applications around trees, vines, and berries. Glufosinate provides control of many annual broadleaf and grass weeds; however, control of large or well-tillered annual grasses, such as yellow or giant foxtail  can be marginal. Glufosinate has no soil activity.

Work conducted by Dr. Brad Majek a few years ago indicated that direct application of glufosinate to the mature brown bark of the lower trunk may cause severe injury by killing the cambium layer at the point of contact (https://plant-pest-advisory.rutgers.edu/glufosinate-products-sold-as-rely-280-expand-as-generic-products-enter-the-market/). However, this type of injury is not systematically associated with glufosinate application as we observed it in a trial conducted in 2017 at the Snyder Research Farm on mature “Pink Lady” apple trees which were not damaged following glufosinate application  (Rely 280 at 64 fl oz/A). Additionally, injury in the form of vertical cracks in the of trunk bark have also be observed on apple trees exposed to glyphosate (https://nyshs.org/wp-content/uploads/2016/10/Pages-23-28-from-NYFQ-Winter-12-12-2013.cmc_.pdf), not only to glufosinate.

As highlighted by Dr. Dave Rosenberg (retired Plant Pathologist at Cornell’s Hudson Valley Lab) on his blog (https://blogs.cornell.edu/plantpathhvl/2014/06/30/apple-summer-diseases-herbicide-problems-and-irrigation/), “NEITHER glyphosate nor glufosinate cause trunk injury to apple trees EVERY time that they are used or in every orchard in which they are applied”. Field reports suggest that injury is detected when trees are exposed to specific conditions that still need to be precisely defined. Dr. Rosenberg’s opinion is that “the potential for damage is significantly higher if tree trunks are hit with either of these herbicides during or just prior to periods of drought stress”. Under these drought conditions, “the additional desiccation from herbicide exposure may predispose the trunks to invasion by Botryosphaeria dothidea, a canker pathogen that is incapable of killing the cambium in healthy functioning trees, but which becomes very pathogenic in drought-stressed trees”. Dr. Rosenberg also suspects that similar injury can be observed on young trees following application of paraquat. Other stress factors, such as cold injury or previous bark damages, may also increase the risk of herbicide injury.

So, to safely apply glyphosate or glufosinate in peaches or apples, it is important following some guidelines that will help minimizing glyphosate or glufosinate damages to the bark:

  • As specified by the label for glufosinate products and the Rutgers 2021-22 E002 Rutgers Tree Fruit guide, contact by the herbicide of parts of trees other than mature brown bark (including suckers) can result in serious damage. It is therefore especially important to protect young trees from potential glufosinate or glyphosate injury by wrapping them with grow tubes or waxed containers.
  • For mature trees, the use of a shield boom is required for minimizing as much as possible contact between the herbicide spray and the tree bark. Shields will also minimize the bounce-back from bare soil that sometimes allows a haze of small droplets to drift upward into the trees.
  • Avoid applications of herbicides during periods when trees are already experiencing water stress or where water-stress can be expected in the near future. Additionally, weed control efficacy of herbicides such as glyphosate of glufosinate can severely decrease when weeds are under heat stress.
  • Keep the pressure as low as possible (no more than 30 psi) to minimize generation of small droplets. If not feasible, use air-induction nozzles to reduce the production of small droplets.
  • Glyphosate should not be applied immediately after suckers are cut because it is readily absorbed by freshly cut stems.
Filed Under: Fruit, Tree Fruit, Wine Grape Tagged With: , , ,
May 26, 2021

Cicadas Are Here and Fruit IPM for 5/26/21

Cicadas are Here, There and Everywhere (Depending where you are): 17 year cicadas began emergence last week. These insects while a marvel in the insect world, are also capable of doing considerable damage to young fruit trees, grape vines, and blueberry bushes. After mating they begin to deposit their eggs in slits along small diameter branches. Thin branches which are loaded with fruit weight and damaged by egg laying can break. Some growers have asked about damage and what they can do to prevent it. Most egg laying is starting this week.

[Read more…]

Filed Under: Blueberry, Fruit, Landscape, Nursery, & Turf, Nursery, Tree Fruit, Wine Grape Tagged With: , , , , , , , , , , , , , ,
April 20, 2021

Tree Fruit IPM Report for April 20, 2021

Tree Fruit Phenology:

Tree Fruit Phenology remains about normal. In southern counties most peach orchards are at petal fall. Redhaven was at approximately full bloom on 4/12, and 90% petal fall on 4/20. Plums are past petal fall and pears are at late bloom to petal fall. Red Delicious is at full bloom. Sweet cherries are at full bloom to late bloom and tart cherries are in bloom. [Read more…]

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April 19, 2021

What to Look for At Bloom: Cankers of Stone fruit.

Bacterial Spot is a key pest of Peach, Nectarine and Plum and in some years like 2019 can cause significant losses. It is caused by the bacterium Xanthomonas arbicola pv. pruni. Bacterial spot cankers that cause tip dieback (commonly called Black Tip) are often difficult to distinguish from cankers caused by other peach diseases. Other cankers that may appear during bloom are caused by the blossom blight phase of brown rot, and constriction canker. Black tip usually appears during or just after bloom. Typical symptoms are a gradual blackening of the tip with dead tissue moving down the twig and is often observed on highly susceptible cultivars (Fig. 1). Tip die back may also occur from abiotic factors such as frost. Tip die back from frost is often accompanied by blind wood usually 6-8 inches below the tip where leaves and flowers have fallen off after being killed by a freeze.

Scared onion

Fig. 1 Tip die back likely bacterial spot or spring frost.

In some cases the twig may appear healthy and a shoot begins growing from the tip only to die back after leafing out and flowering. This is often a symptom of late winter/early spring infections of constriction canker. Many times a bud that was infected in the fall and never leafed out may be found just below the new shoot that is dying. This usually a good clue that constriction canker is the cause. These symptoms may be more prevalent in old trees that have a history of the disease (Fig. 2).

Allium Leaf Miner

Fig. 2 Tip die back possibly caused by constriction canker.

Tip cankers such as these may be accompanied by cankers on flower buds lower down the on the twig typically associated with blossom blight or constriction canker, or they may appear alone. Spring cankers from bacterial spot that form around flower buds are less commonly seen in our region. In cases like this it is difficult to diagnose the disease early on, especially where symptoms are randomly found at low levels or are mixed in appearance. The only thing that can be done is to note the trouble blocks and watch to see what develops. Blossom blight and constriction canker will eventually develop unique symptoms. Bacterial spot lesions will eventually show on the leaves. If you see black tip cankers forming during bloom its not a bad idea to assume its bacterial spot and include copper or oxytetracycline with your blossom blight sprays.

 

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