It is well known in the art to treat tubers such as potatoes with various chemicals having sprout-inhibiting properties. CIPC (chlorpropham, chlorprophame; chlor-IPC IUPAC name isopropyl 3-chlorocarbanilate; isopropyl 3-chlorophenylcarbamate; Chemical Abstracts name 1-methylethyl (3-chlorophenyl)carbamate EEC no. 202-925-7) has been conventionally used for this purpose for about 40 plus years. More recently, chemicals such as various isomers of diisopropylnaphalene and other substituted naphthalenes have exhibited for their sprout-inhibiting characteristics.
Potato tubers are often treated with a chemical sprout inhibitor in the storage season, and may receive another treatment of sprout inhibitor before being packaged for shipment to retail outlets. In the absence of chemical sprout inhibitors, the ultimate storage life is greatly reduced by loss of dormancy and early sprouting. Thus, virtually all potatoes stored mid and long term are treated with chemical sprout inhibitors.
Potatoes when being dug are frequently bruised, cut and/or abraded. These injuries to the potatoes oftentimes cause spoilage during shipment, storage and the like. A process known as suberization occurs naturally which tends to heal many of these injuries. However, whenever potatoes are stored, which occurs with a particularly large portion of potatoes harvested in any given year, if healing occurs slowly, a significant loss of potatoes can occur through spoilage. Early treatment with certain sprout inhibitors, such as CIPC, may retard the suberization process, thus contributing to the loss of potatoes through spoilage.
The main sprout inhibitors registered for use on potatoes are (CIPC), maleic hydrazide (MH), and dimethylnaphthalene (DMN) and Diisopropylnaphthalene (DIPN). The two chemicals in combination (CIPC plus DIPN) appear to be more effective at lower concentrations than either of the two chemicals alone. Simultaneous application of CIPC and DIPN provides improved results over application of either sprout inhibitors separately.
For example, it is relatively common in the potato storage industry to treat potatoes with Chloroisopropyl-N-carbamate (CIPC) to prevent or retard development of sprouts in the potatoes. Even though untreated potatoes are stored at a cool temperature, for example, generally between about 36-52° F., sprouting does begin to occur after a month or more of storage. Storage of upwards of six to ten months is typical for stored potatos. Thus, without treatment of a chemical such as CIPC, the stored potatoes become entangled in sprouts and the whole stored lot of potatoes may become economically useless. Although early treatment with CIPC could be advantageous for sprout inhibition purposes, application of CIPC is typically delayed until after suberization has occurred inasmuch as CIPC tends to retard suberization, resulting in accelerated rot and spoilage.
CIPC is typically applied in one or multiple applications to the tubers to be stored using thermal fogging techniques, sprays and powders. Conventional thermal fogging involving the application of CIPC into a stream of hot air or onto a hot surface of 500-1000 ° F., to produce a CIPC aerosol. The CIPC aerosol is circulated through potatoes piled in a potato storage building with the use of fans. Preferably the potatoes are turgid rather than soft when treated with the CIPC aerosol, since a pile of softened potatoes may be substantially compressed thereby impeding distribution of the aerosol. CIPC residue levels, will, however, typically decrease over time due to biodegration, venting and atmospheric loss. To extend the effective sprout inhibiting capability of CIPC, further applications may be needed.
CIPC is used in significant quantities world wide and is capable of suppressing sprouts on stored tubers with the chemical ability to limit cell division. Increased rates, multiple applications, addition of substituted naphthalene chemistries coupled with strict storage management strategies have been implemented to help reduce sprout development in CIPC treated potatoes. Yet the tubers often develop swollen white bud tissue and small peeping sprouts that are undesirable and when present can reduce the fresh pack potato value from 50% to 100% (complete rejection) at the point of delivery. The instant invention provides, among other things, an effective treatment protocol that darkens and/or burns back these unwanted buds and small sprouts and allows the potatoes to be wholly valued in the market and compliments the use of CIPC. It also provides assurance of less shrink (weight loss) and maintains the tuber quality over and above the use of CIPC EC alone.